Passion - Blessing Or Curse?

Lately, I've been wondering about people's passion for life and for what they do. What makes us get up every morning? What motivates us to train for athletic competitions? What keeps us going?

Yea, part of it is basic survival and such. Everybody wants a warm place to sleep, food and some creature comforts. Still, I believe that life is more fulfilling and fun when you have passion for something. A passion that burns inside of you. A passion that forces you to work harder, do better, try again:

Only passions, great passions, can elevate the soul to great things.
Denis Diderot

In a way, I'm still searching for my great passion in life. Well, I wouldn't mind more than one passion, actually. I like a lot of things. I have been decent at most stuff I tried, whether it was school/job-related or some kind of free-time activity.
I have never had a job I despised or didn't like. I guess you could even say that I felt somewhat passionately about all of them.
To this day, it pisses me off when people bitch and moan about the German post office, for example. Seriously, 98% of letters get to their destination the day after they were mailed. How fucking awesome is that?
Hehe.

Hmm. So I do get excited and passionate about a lot of things (running, language, teaching, writing,...quite a few more), but I've never been driven by this deep passion for one career or hobby. That's why I'm stuck in this limbo, I guess. I have no singular passion that steers me towards my next, more fulfilling, more challenging job...

I envy my middle brother in a way. He has this insane drive to be a musician. Always has, always will.

(Evidence)

My brother's daytime job is a way to make ends meet. Don't get me wrong, he's good at it and does it well. Still, his passion in life is music. Sometimes it gets him down that he cannot support himself with music alone, that it's insanely competitive out there, that some of the richest 'musicians' are plastic marketing tools.
Nevertheless, he keeps on doing what he loves. His passion never waivers. And that's just awesome.