Best advice I received was from my dad - in life you have three different types of inner motivation:
* fire and anger are the initial drive - they help you start something
* professionalism and existentialism - they help keep you going
* self-fulfillment - they help you finish
One motive that is inwrought through all these motivators is "sometimes you have to be your own hero". You have to have the fire, you have to have the professionalism, you have to fulfilled. Not others. Step it up, I'm sure you have it in you!
Don't give up, your life has purpose and you are valuable :)