"Fail often" is a good piece of advice you've heard before, but chances are nobody's ever told you to "quit often". Maybe it's time you started.
Alex Lickerman, writing for Psychology Today, suggests that we quit thanks to our incredibly powerful imaginations. When starting to run again after recovering from a knee injury, Lickerman experienced this problem himself:
Our minds are so good at imagining things that once mine had begun to think about the end of my run, reaching the end of my run-and therefore the end of my pain-was all I could think about. The idea that my pain was about to end became so enticing that my ability to withstand it dramatically declined.
Lickerman suggests that quitting isn't necessarily the end of the world, however, because the important thing is that we're making the effort in general. Just as we have to fail often to find success, we need to accept failure when our minds overwhelm us. We made the effort, we did a pretty good job, and failing to make it to the finish line doesn't mean we can't try again tomorrow. If you feel pressured to quit when something is difficult, you may find yourself better off by quitting and trying again tomorrow. So long as you continue to try, you haven't really quit at all.
Why We Quit | Psychology Today