How to decide what to do, according to Derek Sivers:

I have some easy rule-of-thumbs to follow

1. whatever excites you, go do it
2. whatever scares you, go do it
3. every time you’re making a choice, one choice is the safe/comfortable choice - and one choice is the risky/uncomfortable choice. the risky/uncomfortable choice is the one that will teach you the most and make you grow the most, so that’s the one you should choose.

source: http://sivers.org/scares-excites-do-it