Human beings have a natural need to avoid and/or resolve discomfort of any kind. Humans also have a need to see themselves develop and experience pleasure also. This is evident in the amazing achievements of elite performers who take the balance of massive discomfort and great developmental achievements to often unknown limits. The human quest for joy and fulfillment of potential begins to explain the many sacrifices people make for sports, for art and for all sorts of human endeavor.
In my work, I guide people to adopt a rational philosophy. Rational living was first introduced in the 1950's by Dr. Albert Ellis, the founding father of cognitive behavioral therapy. The main stance of rational thinking is that humans tend to form irrational beliefs. Irrational beliefs are static, extreme views of how people think things are or how they would prefer them to be. Now, irrational beliefs are great at motivating action (e.g. I should be better than this) but, use them wisely because they are equally good at getting right in the way of goal achievement.
Here's an easy example to start with. When was that last time you said, "I can't stand it when that happens....” It's a common phrase that lots us use without even realising that we have used it.
Telling yourself "I can't stand feeling out of breath, under pressure, being scrutinised by an audience, the weather, the opponent, the referee or the situation that I'm in" is a false and irrational belief that will only help you to avoid situations that lead you forward towards your goal. It is a false belief because the fact that you are there and that you endure the situation which you apparently "can't stand" is proof that you can, in fact, stand it... no matter how bad or uncomfortable it seems...look at you... you are standing it.
A great source of human unhappiness and failure to move towards goals is people's belief that they can't stand certain events that, while tough; distressing; not to one’s liking; unfair or inconvenient are endurable. Holding the strong and apparently very real view that something is so difficult, so challenging, so uncomfortable that you literally can't stand it will never help you achieve a challenging goal.
If your "can't stand its" are getting in between you and progress or happiness change them. Adopt a rational perspective and practice that perspective until it becomes second nature. Practice this new perspective in three ways, think it... so instead of "I can't stand it" use "I really don't like this, but I can stand it" and actively behave or move differently, adapt. Relax yourself and notice that you can stand the pressure and remember the long-term aim. Importantly, notice how you feel. You won't like the way you feel. You don't have to like the way you feel to stand the pressure or the situation that you previously believed you couldn't stand.