user701: I've seen some people do this. But how practical is this with the modern lifestyle? As an example the place where I sit in the office is a bit too comfortable. Sometimes there's music in public transport.  If that person shares a place with others or visits other people, they may have to change their lifestyles as well. e.g: eating before noon.
How can one deal with such situations without being a nuisance to others, if someone decides to observe them in day-to-day life?

user-1: Dmps, and those interested,
Upasaka Akila once asked similar question and did that at least with success: here as introducing encouragement (incl. those of the Buddha, in the links of the answer).
Kepping the eight percepts, even if not everyday, is for sure one of the clear signs that one is a serious and discerning follower of the Buddha, one with possible success and upwards (not only even) walking.
It's not so that it is a matter of "modern" or "earlier" life but timeless a matter of unskillful and skillful lifestyle. In all times there have been people just used to "modern" (e.g. beloved by many) life.
Practicing the Dhamma means to give, give up and withdraw (from unskilful deeds and way of life) and the eight precepts help where the defilements would be strong in arguing, like here an now.
Like with precets and virtue generally, it requires faith at first place and just following, because the tesults are unknown, can not be seen for now.
Best is possible to make it step by step. To start with one precept, add another, make one better, and so on.
How ever, it's good and useful to request them also formal from a monk/s or nun/s and to take/ask refuge before. Such does not only provide good sphere for questions but gives also a subtile and powerful drive.
In regard of precepts-training generally, this topic might be useful: Obsering the (5) precepts (it work for all similar.
Some "technical" explainings, althought my person is no friend of them, since taken from the Vinaya and not from the Suttas, with Commentary additions (good for wise, bad for not so wise), here:
Ñanavara Thera's Questions-and-answers concerning the Uposatha. and more infos and links here.
Generally suggest: it's good and needed to have, if no Community of monks, or a monk, is near, good friends who do and who are able to help. So to seek for like-minded or better companions would be the main task. Obiviously merely seldom to be found on common places.
Just short to you particular questions: 

It's possible to chose modest sears anyway.
It's good to reduce the amount of meals, take no snakes an eat at fix time, also if maybe another timeframe. How ever, changing ones lifestyle and livelihood is natural and will be done.
Being confronted with entertainment is something out of ones controll, but to pay it attention, go after it, sing in mind... not. Giving up all foolish entertainments is very useful, at least also for ones wealth. Avoiding the entertainment by news and politic brings bliss.

Things get known when doing, so don't wast time. Tomorrow is not for sure to be and even one day observed is of great fruits, not to speak about sticking with it.
Mudita.
If questions or need of advices, always welcome, having lived a live of 5, 8, 9, 10 precepts serious still a lay person, there is knowing that it is possible and of benefit.

[Note: This is a gift of Dhamma and not meant for commercial purpose or other low wordily gains by means of trade and exchange.]

user533: Lay people used to do that once a week in the time of the Buddha, as you are not a monk, you can keep only the 5 precepts on week days and select one day of the weekend to keep the 8 precepts.
One of the teachers I like (Banthe Dhammavudo Thero) from theravada tradition recommends that practice.
If you try to live a monk's life as a lay person, having to work etc... you will be in a hard position, unfortunately!

user690: if you are offered a seat that seems luxurious, and simply using the seat available, as opposed to seeking out "the best seat" your intention is appropriate.
if you hear music someone else is playing, its very different from intentionally seeking out music to listen to.
these are very useful opportunities to meditate on the nature of such phenomina and your reaction to them. like, if your mind tries to attach to the other persons music, or if you experience gladness about being stuck with a nice seat.
others conforming to your lifestyle is not necessary (and may be inappropriate, especially if you impose your beliefs on them) no one else can violate your precepts for you.
understanding things in this way may be helpful.
one example... if someone has to go out of their way to accommodate a low seat (a specific preference) then that seat becomes (in a way) a phenomenon of luxury.

user745: Simply being in the presence of music or entertainment or sitting in a comfortable chair doesn't break the 8 precepts. Here are the relavent descriptions from the Uposatha Sutta in which the Buddha describes the 8 precepts:

All of you have given up singing and dancing, the playing of musical
  instruments and the watching of entertainments, which are stumbling
  blocks to that which is wholesome. You do not bedeck yourselves with
  ornaments, flowers or perfume. For all of this day and night, in this
  manner, you will be known as having followed the arahants, and the
  Uposatha will have been observed by you. This is the seventh factor of
  the Uposatha.
...
All of you have given up lying on large or high beds. You are content
  with low beds or beds made of grass. For all of this day and night, in
  this manner, you will be known as having followed the arahants, and
  the Uposatha will have been observed by you. This is the eighth factor
  of the Uposatha.
http://www.accesstoinsight.org/tipitaka/an/an08/an08.041.vaka.html

With entertainment it is talking about intentionally seeking out or producing entertainment, not about overhearing or seeing someone else doing it, and the giving up of high beds I think is specifically refering to the use of such beds to sleep. I don't think sitting in a chair counts.
Furthermore whenever we interpret the precepts as laypeople (i.e., not interpreting the rules of Vinaya) we have to focus on the underlying principle and purpose of the precepts to decide between different understandings. The purpose of the eight precepts is to live with the renunciation of sensuality and luxury. As a layperson I think it makes sense to say that as long as you are not actively seeking these things out but merely coming across them, you are still acting in accordance with renunciation.

701: <p>I've seen some people do this. But how practical is this with the modern lifestyle? As an example the place where I sit in the office is a bit too comfortable. Sometimes there's music in public transport.  If that person shares a place with others or visits other people, they may have to change their lifestyles as well. e.g: eating before noon.</p>

<p>How can one deal with such situations without being a nuisance to others, if someone decides to observe them in day-to-day life?</p>
 -1: <p>Dmps, and those interested,</p>

<p>Upasaka <a href="https://buddhism.stackexchange.com/questions/20932/upostha-sila-in-normal-daily-life/20941#20941">Akila once asked similar question</a> and did that at least with success: here as introducing encouragement (incl. those of the Buddha, in the links of the answer).</p>

<p>Kepping the eight percepts, even if not everyday, is for sure one of the clear signs that one is a serious and discerning follower of the Buddha, one with possible success and upwards (not only even) walking.</p>

<p>It's not so that it is a matter of "modern" or "earlier" life but timeless a matter of unskillful and skillful lifestyle. In all times there have been people just used to "modern" (e.g. beloved by many) life.</p>

<p>Practicing the Dhamma means to give, give up and withdraw (from unskilful deeds and way of life) and the eight precepts help where the defilements would be strong in arguing, like here an now.</p>

<p>Like with precets and virtue generally, it requires faith at first place and just following, because the tesults are unknown, can not be seen for now.</p>

<p>Best is possible to make it step by step. To start with one precept, add another, make one better, and so on.</p>

<p>How ever, it's good and useful to request them also formal from a monk/s or nun/s and to <a href="http://sangham.net/index.php/topic,1952.0.html#post_engl" rel="nofollow noreferrer">take/ask refuge</a> before. Such does not only provide good sphere for questions but gives also a subtile and powerful drive.</p>

<p>In regard of precepts-training generally, this topic might be useful: <a href="http://sangham.net/index.php/topic,8183.0.html" rel="nofollow noreferrer">Obsering the (5) precepts</a> (it work for all similar.</p>

<p>Some "technical" explainings, althought my person is no friend of them, since taken from the Vinaya and not from the Suttas, with Commentary additions (good for wise, bad for not so wise), here:
<a href="http://zugangzureinsicht.org/html/lib/authors/nanavara/uposatha_en.html#qa" rel="nofollow noreferrer">Ñanavara Thera's Questions-and-answers concerning the Uposatha.</a> and more <a href="http://zugangzureinsicht.org/html/ptf/dhamma/sila/atthasila_en.html" rel="nofollow noreferrer">infos and links</a> here.</p>

<p>Generally suggest: it's good and needed to have, if no Community of monks, or a monk, is near, good friends who do and who are able to help. So to seek for like-minded or better companions would be the main task. Obiviously merely seldom to be found on common places.</p>

<p>Just short to you particular questions: </p>

<ul>
<li><p>It's possible to chose modest sears anyway.</p></li>
<li><p>It's good to reduce the amount of meals, take no snakes an eat at fix time, also if maybe another timeframe. How ever, changing ones lifestyle and livelihood is natural and will be done.</p></li>
<li><p>Being confronted with entertainment is something out of ones controll, but to pay it attention, go after it, sing in mind... not. Giving up all foolish entertainments is very useful, at least also for ones wealth. Avoiding the entertainment by news and politic brings bliss.</p></li>
</ul>

<p>Things get known when doing, so don't wast time. Tomorrow is not for sure to be and even one day observed is of great fruits, not to speak about sticking with it.</p>

<p>Mudita.</p>

<p>If questions or need of advices, <a href="http://sangham.net/index.php/board,38.0.html" rel="nofollow noreferrer">always welcome</a>, having lived a live of 5, 8, 9, 10 precepts serious still a lay person, there is knowing that it is possible and of benefit.</p>

<hr>

<p><em>[Note: This is a gift of Dhamma and not meant for commercial purpose or other low wordily gains by means of trade and exchange.]</em></p>
 533: <p>Lay people used to do that once a week in the time of the Buddha, as you are not a monk, you can keep only the 5 precepts on week days and select one day of the weekend to keep the 8 precepts.</p>

<p>One of the teachers I like (Banthe Dhammavudo Thero) from theravada tradition recommends that practice.</p>

<p>If you try to live a monk's life as a lay person, having to work etc... you will be in a hard position, unfortunately!</p>
 690: <p>if you are offered a seat that seems luxurious, and simply using the seat available, as opposed to seeking out "the best seat" your intention is appropriate.</p>

<p>if you hear music someone else is playing, its very different from intentionally seeking out music to listen to.</p>

<p>these are very useful opportunities to meditate on the nature of such phenomina and your reaction to them. like, if your mind tries to attach to the other persons music, or if you experience gladness about being stuck with a nice seat.</p>

<p>others conforming to your lifestyle is not necessary (and may be inappropriate, especially if you impose your beliefs on them) no one else can violate your precepts for you.
understanding things in this way may be helpful.</p>

<p>one example... if someone has to go out of their way to accommodate a low seat (a specific preference) then that seat becomes (in a way) a phenomenon of luxury.</p>
 745: <p>Simply being in the presence of music or entertainment or sitting in a comfortable chair doesn't break the 8 precepts. Here are the relavent descriptions from the Uposatha Sutta in which the Buddha describes the 8 precepts:</p>

<blockquote>
  <p><strong>All of you have given up singing and dancing, the playing of musical
  instruments and the watching of entertainments</strong>, which are stumbling
  blocks to that which is wholesome. You do not bedeck yourselves with
  ornaments, flowers or perfume. For all of this day and night, in this
  manner, you will be known as having followed the arahants, and the
  Uposatha will have been observed by you. This is the seventh factor of
  the Uposatha.</p>
  
  <p>...</p>
  
  <p><strong>All of you have given up lying on large or high beds. You are content
  with low beds or beds made of grass.</strong> For all of this day and night, in
  this manner, you will be known as having followed the arahants, and
  the Uposatha will have been observed by you. This is the eighth factor
  of the Uposatha.</p>
  
  <p><a href="http://www.accesstoinsight.org/tipitaka/an/an08/an08.041.vaka.html">http://www.accesstoinsight.org/tipitaka/an/an08/an08.041.vaka.html</a></p>
</blockquote>

<p>With entertainment it is talking about intentionally seeking out or producing entertainment, not about overhearing or seeing someone else doing it, and the giving up of high beds I think is specifically refering to the use of such beds to sleep. I don't think sitting in a chair counts.</p>

<p>Furthermore whenever we interpret the precepts as laypeople (i.e., not interpreting the rules of Vinaya) we have to focus on the underlying principle and purpose of the precepts to decide between different understandings. The purpose of the eight precepts is to live with the renunciation of sensuality and luxury. As a layperson I think it makes sense to say that as long as you are not actively seeking these things out but merely coming across them, you are still acting in accordance with renunciation.</p>
