user157: In the Triratna Buddhist Community we do a practice that we call Just Sitting. It's described as

Just Sitting is a space of non-action in which anything can emerge.
  Often the fruit of the previous practice only emerges when you stop
  ‘doing’ it. And Just Sitting is the non-doing space in which that may
  (or may not) happen. Just Sitting also allows assimilation of what has
  just been done, and provides the necessary counterpoise to activity
  and effort. Just Sitting is a matter of simply ‘being’ with whatever
  happens in awareness, without attaching to it or rejecting it.

Link to quote is here. 
I've always wondered if this is something that we've just kind of invented or adapted or is it common to other Buddhist traditions? Is it the same as zazen practice perhaps?

user832: Zen Mind Beginner's Mind by Shunryu Suzuki might offer you the perspective that goes beyond words to intention. If we aim at beginner's mind, then just sitting or zazen or meditation is aiming at beginner's mind. The intention of the person sitting is the most significant factor. 
There are times I have fallen asleep sitting. Perhaps I was tired or my intention was not clear.
Other times when intention is clear the sitting becomes the bow, the awareness the arrow and intention the one drawing the bow. When intention draws the bow, the arrow cannot miss the mark.
Here is a copy of the book. Sip a page or two at a time and report back in a year - me saying words will not draw the bow.
http://www.arvindguptatoys.com/arvindgupta/zenmind.pdf

user745: The term Zazen (Chinese 坐禪, zuò chán) just means seated meditation. It doesn't itself specify what kind of meditation is being practiced.
Just Sitting refers to Shikantaza, which is the type of meditation taught by Dōgen Zenji, the founder of the Sōtō school of Japanese Zen. He famously explained it in the Fukanzazengi saying :

Once you have adjusted your posture, take a breath and exhale fully,
  rock your body right and left, and settle into steady, immovable
  sitting. Think of not thinking. Not thinking-what kind of thinking is
  that? Nonthinking. This is the essential art of zazen.

There are similar practices in other schools of Zen in China and Korea, but it is less prominent as Koan practice is more common. 

157: <p>In the <a href="https://thebuddhistcentre.com/" rel="nofollow">Triratna Buddhist Community</a> we do a practice that we call Just Sitting. It's described as</p>

<blockquote>
  <p>Just Sitting is a space of non-action in which anything can emerge.
  Often the fruit of the previous practice only emerges when you stop
  ‘doing’ it. And Just Sitting is the non-doing space in which that may
  (or may not) happen. Just Sitting also allows assimilation of what has
  just been done, and provides the necessary counterpoise to activity
  and effort. Just Sitting is a matter of simply ‘being’ with whatever
  happens in awareness, without attaching to it or rejecting it.</p>
</blockquote>

<p>Link to quote is <a href="https://thebuddhistcentre.com/text/just-sitting" rel="nofollow">here</a>. </p>

<p>I've always wondered if this is something that we've just kind of invented or adapted or is it common to other Buddhist traditions? Is it the same as zazen practice perhaps?</p>
 832: <p>Zen Mind Beginner's Mind by Shunryu Suzuki might offer you the perspective that goes beyond words to intention. If we aim at beginner's mind, then just sitting or zazen or meditation is aiming at beginner's mind. The intention of the person sitting is the most significant factor. </p>

<p>There are times I have fallen asleep sitting. Perhaps I was tired or my intention was not clear.</p>

<p>Other times when intention is clear the sitting becomes the bow, the awareness the arrow and intention the one drawing the bow. When intention draws the bow, the arrow cannot miss the mark.</p>

<p>Here is a copy of the book. Sip a page or two at a time and report back in a year - me saying words will not draw the bow.</p>

<p><a href="http://www.arvindguptatoys.com/arvindgupta/zenmind.pdf" rel="nofollow">http://www.arvindguptatoys.com/arvindgupta/zenmind.pdf</a></p>
 745: <p>The term Zazen (Chinese 坐禪, zuò chán) just means seated meditation. It doesn't itself specify what kind of meditation is being practiced.</p>

<p>Just Sitting refers to Shikantaza, which is the type of meditation taught by Dōgen Zenji, the founder of the Sōtō school of Japanese Zen. He famously explained it in the Fukanzazengi saying :</p>

<blockquote>
  <p>Once you have adjusted your posture, take a breath and exhale fully,
  rock your body right and left, and settle into steady, immovable
  sitting. Think of not thinking. Not thinking-what kind of thinking is
  that? Nonthinking. This is the essential art of zazen.</p>
</blockquote>

<p>There are similar practices in other schools of Zen in China and Korea, but it is less prominent as Koan practice is more common. </p>
