We thought it was so easy

But it actually takes 10,000 hour to master something. That's 2 hours everyday for 14 years. A Freaking long time.

Logically you gotta choose carefully if you wanna invest 10,000 in mastering something. But you can't. 'Cause you won't know what you want.

If you're passed 20 you should know what you sucks at though, so don't invest in those. Invest in your core competencies -- to paraphrase Peter Drucker.

Dilbert author has an interesting advice -- Be very good at two or more things. It takes so much effort to be the top 5% at something, but not so much for top 25% at two things. And you'll also be in a unique position, it's rare to have a combination of skills. "Queen of two trades"

So Invest about 7,000 hours into two or more things, and you'd do great!... in 20 years. :)