user10389: 
'Pain is inevitable. Suffering is optional.'

I'm not sure I like the adjective 'optional' because I think it's insensitive to tell someone who's been injured that their suffering is some switch to easily flip (I don't have an issue with the nouns). I think 'not' is better than 'optional'.
Anyhoo, many Dialectical Behavioural Therapy (DBT) texts seem to distinguish pain and suffering in other ways such as:

Psychology Today: The Dialectic of Pain: Synthesizing Acceptance and Change

Pain in life is inevitable, but suffering and misery are not. These can result from the way we respond to pain. The more we fight against it, the more likely we are to experience negative emotions, such as anger, hopelessness, and despair, and the harder it becomes to identify changes that can help. Like those Chinese finger-trap toys, the more forcefully we tug to release our index fingers, the more tightly ensnared they become. Calming down and taking stock of the situation opens the means to escape.


Wikipedia: Marsha M. Linehan (this quote has no source as of this writing)

Marsha M. Linehan (born May 5, 1943) is an American psychologist and author. She is the creator of dialectical behavior therapy (DBT), a type of psychotherapy that combines behavioral science with Buddhist concepts like acceptance and mindfulness.


And so on.



user43: Generally speaking, "Buddhism is like Christianity" - in the sense that it has many different schools and sects that have their own practices and disagree on interpretations.
However, when it comes to suffering vs pain, most Buddhist nominations should agree with that statement. In fact I suspect this entire idea was taken by DBT from Buddhism. Suffering is not the best word for dukkha though, hence your confusion/resistance. Dukkha is the painful feeling we have when things are wrong and we can't do much about it.
If that makes you feel better, here is the same phrase in some alternative renditions:

'Pain is inevitable. Unhappiness is optional.'
'Pain is a part of life. Frustration is up to you.'

The idea is that external circumstances are not in our control, even our state of mind is not always in our control... but our attitude - our deep inner peace - is entirely up to us. Even if we're in pain and dying, we can be at peace an die gracefully, can't we? Let alone when we have normal difficulties.
This idea is slightly more palatable than telling someone their suffering is self-inflicted, but even this may be hard to accept for someone used to being in the victim consciousness. We're very used to explaining our unhappiness in terms of the circumstances. But as my Zen Master used to say, keeping our mind clean from unhappiness is like keeping our kitchen clean from the cockroaches. It is entirely our responsibility. In fact, rather than feeling pity for ourselves for being unhappy - we should be ashamed of not keeping our "kitchen" clean.
This is Emotional Intelligence 101, and a lot of it comes from Buddhism. Consider the Four Right Efforts:

... monks, you should apply effort toward:
  - non-arising of bad, pathological states of mind that have not yet arisen.
   - abandonment of bad, pathological states of mind that have arisen.
   - arising of wholesome states of mind that have not yet arisen.
   - maintenance and development of wholesome states of mind that have arisen.  

Even the Noble Truth itself is a form of the same principle. The core idea is that dukkha (unhappiness, frustration) comes from an inner conflict. Conflict between how things "should be" and how they "are" - both sides modeled by our mind. The Buddhist path leads a person to the ultimate state of peace called "suchness" (tathata) - the state when "is" and "should" is no longer in conflict. This is achieved through a combination of objective (behavioral) changes in one's lifestyle and subjective (attitude) changes in one's psyche.
Buddhist Nirvana is the culmination of this path from conflict to suchness.

10389: <blockquote>
<p>'Pain is inevitable. Suffering is optional.'</p>
</blockquote>
<p>I'm not sure I like the adjective 'optional' because I think it's insensitive to tell someone who's been injured that their suffering is some switch to easily flip (I don't have an issue with the nouns). I think 'not' is better than 'optional'.</p>
<p>Anyhoo, many Dialectical Behavioural Therapy (DBT) texts seem to distinguish pain and suffering in other ways such as:</p>
<ul>
<li><p><a href="https://www.psychologytoday.com/blog/paintracking/201303/the-dialectic-pain-synthesizing-acceptance-and-change" rel="nofollow noreferrer">Psychology Today: The Dialectic of Pain: Synthesizing Acceptance and Change</a></p>
<blockquote>
<p>Pain in life is inevitable, but suffering and misery are not. These can result from the way we respond to pain. The more we fight against it, the more likely we are to experience negative emotions, such as anger, hopelessness, and despair, and the harder it becomes to identify changes that can help. Like those Chinese finger-trap toys, the more forcefully we tug to release our index fingers, the more tightly ensnared they become. Calming down and taking stock of the situation opens the means to escape.</p>
</blockquote>
</li>
<li><p><a href="https://en.wikipedia.org/wiki/Marsha_M._Linehan" rel="nofollow noreferrer">Wikipedia: Marsha M. Linehan</a> (this quote has no source as of this writing)</p>
<blockquote>
<p>Marsha M. Linehan (born May 5, 1943) is an American psychologist and author. She is the creator of dialectical behavior therapy (DBT), a type of psychotherapy that combines behavioral science with Buddhist concepts like acceptance and mindfulness.</p>
</blockquote>
</li>
<li><p>And so on.</p>
</li>
</ul>
 43: <p>Generally speaking, "Buddhism is like Christianity" - in the sense that it has many different schools and sects that have their own practices and disagree on interpretations.</p>

<p>However, when it comes to suffering vs pain, most Buddhist nominations should agree with that statement. In fact I suspect this entire idea was taken by DBT from Buddhism. Suffering is not the best word for <code>dukkha</code> though, hence your confusion/resistance. <code>Dukkha</code> is the painful feeling we have when things are wrong and we can't do much about it.</p>

<p>If that makes you feel better, here is the same phrase in some alternative renditions:</p>

<blockquote>
  <p>'Pain is inevitable. Unhappiness is optional.'</p>
  
  <p>'Pain is a part of life. Frustration is up to you.'</p>
</blockquote>

<p>The idea is that external circumstances are not in our control, even our state of mind is not always in our control... but our <em>attitude</em> - our deep inner peace - is entirely up to us. Even if we're in pain and dying, we can be at peace an die gracefully, can't we? Let alone when we have normal difficulties.</p>

<p>This idea is slightly more palatable than telling someone their suffering is self-inflicted, but even this may be hard to accept for someone used to being in the victim consciousness. We're very used to explaining our unhappiness in terms of the circumstances. But as my Zen Master used to say, keeping our mind clean from unhappiness is like keeping our kitchen clean from the cockroaches. It is entirely our responsibility. In fact, rather than feeling pity for ourselves for being unhappy - we should be ashamed of not keeping our "kitchen" clean.</p>

<p>This is Emotional Intelligence 101, and a lot of it comes from Buddhism. Consider the <a href="https://en.wikipedia.org/wiki/Four_Right_Exertions" rel="nofollow noreferrer">Four Right Efforts</a>:</p>

<blockquote>
  <p>... monks, you should apply effort toward:<br>
  - non-arising of bad, pathological states of mind that have not yet arisen.<br>
   - abandonment of bad, pathological states of mind that have arisen.<br>
   - arising of wholesome states of mind that have not yet arisen.<br>
   - maintenance and development of wholesome states of mind that have arisen.  </p>
</blockquote>

<p>Even the Noble Truth itself is a form of the same principle. The core idea is that <code>dukkha</code> (unhappiness, frustration) comes from an inner conflict. Conflict between how things "should be" and how they "are" - both sides modeled by our mind. The Buddhist path leads a person to the ultimate state of peace called "suchness" (tathata) - the state when "is" and "should" is no longer in conflict. This is achieved through a combination of objective (behavioral) changes in one's lifestyle and subjective (attitude) changes in one's psyche.</p>

<p>Buddhist Nirvana is the culmination of this path from conflict to suchness.</p>
