Training in martial arts is an exercise in invincibility. You want to learn all of the possible attacks that can be used against you and then find a solution to those problems.
Applying this philosophy to life is a powerful exercise. To be able to experience the bad and then with expert precision decide how you want to feel about it. Let me give you one easy example: The next time you are exhausted wether from physical labor or life activity - feel grateful for it. The weariness is still present but you are not pushing against it. You enjoy the feeling knowing that you are living a full life and making progress. You are proud that you maximized your effort and exceeded your limits, instead of beating yourself up for not having enough endurance to do more.
It's the pushing against unpleasant emotions that makes them more difficult to bare.