There is a long list of things I couldn't do professionally, even if it was my life's dream:

Sing, or play any type of instrument
Compete in any sport
Sculpt or paint
Make a run for office
Model
Be a game warden (got a bad eye)
Teach
Dance
Juggle
Be an astronaut
Perform magic
Perform stand-up comedy

The list goes on, but those are some obvious examples. But here's the thing: I KNOW I can't do any of those things, so I don't try. If I did try--not just as a hobby, but as a career--it would be a waste of time. I'd be in the poorhouse.

So why do so many people on American Idol absolutely suck? Sometimes you can tell that somebody is auditioning just as a goof, but there are others who honest-to-God think they can sing, that it's their calling, even when they sound like a sick parrot.

Yet...

When people have a dream to make it in some arena of the "arts," they very frequently hear that they should never abandon their dreams. Just keep trying! You'll make it someday! That, my friends, is bad advice. Yes, in fact, you should abandon your dreams, and abandon them right this minute.

But hold on. I'm not saying you shouldn't dream, just base your dream in reality. Just because you can't sing, maybe you CAN dance. Or maybe not, in which can maybe you can sculpt. Or be a hell of a teacher. Or fly to the moon.