How can you “feel better” if “live is always 50-50”?

Hi there! There’s courses and skills on how to feel better, but Brooke always refers to how when aiming for a goal, it’s not going to help you to think “I want to lose weight because I think I’ll feel better.” What’s more helpful is to “feel better now before you get to the goal and actually in ORDER to get to the goal.” But this can’t be possible if life is always 50-50. Can you please explain? Thanks so much!!