Observe and learn your habits and emotions. Journal, analyze, and exploit your findings. Can help reduce struggles or improve performance; most of all, learn to know yourself and work with yourself.

Also, discipline isn't a bad word: discipline isn't to do things you hate, but is to follow what you truly want.

Perspective matters. You're a radio and you can learn to (partially) tune yourself into what you want to hear; you're almost never just feeling a single emotion.

Also the root of all emotions, including negative ones, is love. Though this sounds like bullshit and isn't very useful until you've reached a certain point.