Passion? I'm the same way. When I was a kid, coding 18 hours a day for weeks at a time wasn't a problem during summer vacations. Now, I have trouble with it. Full time job just DRAINS me, I don't want to do shit.

However, I discovered a passion. Illustration and UI/UX design for mobile. Every day after work I've been working an extra 8 hours because I found it so FUN.

So much so I have people working for me full time now and I'm quitting my job soon to follow my passion.

Maybe you haven't found your "calling" or something to get extraordinarily obsessed about?