Back when Bell Labs was a top research institute, some researcher gave an interview. He noted that he was top of his class in high school. Way up there in college. Pretty good in grad school. Then he was hired at Bell Labs, where he was at best average. Man, he just got dumber and dumber as time went on.

He said it with a smile, but still, there's a hard kernel of truth there for many of us: if we work hard to advance, and put ourselves in the company of top people, we no longer stand out. But you know what? Life needn't be a continual competition. Be good at what you do, do it well, and take satisfaction in that. You don't need to continuously compare yourself to everyone else, and ask if you are in the top 10%. Eventually you won't be, if only because your entire group is up there.

...look at nature: The best do what they can and the weak suffer.

Yes, but we aren't surrounded by hyenas in the wilds of Africa. Civilization does bring some benefits. Take some time to smell the roses. Heck, a bit of time for relaxation may even improve your performance.