After reading chapter ten, the excellence curse? I don't know that i would continue to have that viewpoint. The easy answer is, something you're good at that you would consider one of your core talents. But it gets messy when you start trying to nail downw what qualifies as being good at it. That's where the messy park comes into play. He mentions on page one 16, that where there is no love the activity is a weakness even if you excel at it.