Depressing question: To what extent would you give up on difficult goals, if you knew the odds were against you?

Specifically, if you had to overcome large obstacles that other people don’t necessarily face. Say you had a disability, for instance. You have a goal that is hard for even a “normal” person to achieve, that is fairly stressful to strive towards. You know the payoff is unlikely to occur, and your life would be easier if you weren’t working towards it. But if by chance you did achieve your goal, it would be extremely fulfilling.

How readily would you “give up;” acknowledge that the payoff is unlikely and your life would be easier if you didn’t bother striving towards a nearly impossible goal?
Or, do you think you would refuse to allow your disability to defeat you, and continue to strive against the odds?