As an athlete, you'll never feel bad about losing, but what you will feel bad about is underperforming. That's a real thing and it happens a lot when we don't live up to our potential. And that keeps you up at night and can give you years and years of regret. It could be a relationship, it could be a homework assignment, or it could be an athletic competition. If you don't go out and perform to the best of your ability, it will really bother you.