Many musicians get into music because they LOVE playing drums, for example. They love it so much they want to do it for a living. But then the world says, “If you're going to be in the music business, you have to understand cross-collaterization! You have to read this book on music business law. And you need a great website. So you have to learn HTML. And Flash. And how to stream audio files on the web. And you need to understand marketing, and accounting, and etc etc etc....”
Soon this drummer is spending all his time doing everything BUT play the drums, and decides it's not worth it! He gets a job at a bank and loses interest in his drums, because a career in music now seems like the most awful thing ever.
Yes, the people who said he should know all that stuff meant well, but nothing is worth losing your enthusiasm. NOTHING!
You have to pay close attention to that compass, even in little day-to-day decisions. You get offered a gig - they're on the phone waiting for an answer - is it exciting you or draining you? To make a new website is going to take about 10 hours of work. Does that excite you or drain you?
If it doesn't excite you, don't do it.
There's almost nothing that you MUST do. Someone somewhere is excited to do the things that drain you. Find them and let them do it.
Work towards this ideal, and soon you'll be doing only what excites you the most, all day. Then you'll find that doors open for you, opportunities come your way, life seems to go easier, because you're doing what you're meant to do.