(This post is part of a bigger list of rules that I have found helpful for thinking about a career, and beyond. See this post for an explainer).
Comparing yourself to others is perhaps the greatest source of self-inflicted unhappiness there is. Unfortunately in academia, it's rampant. But by realizing that this is a major source of stress, you can better recognize when you fall victim to it, and try to ease its negative effects.
No matter how hard you try, there will always be someone who is better than you. It's a mathematical necessity for all but one person. The day you come to terms with this reality is the day you become more relaxed, and being relaxed makes you perform better (as already indicated in rule 9).
That doesn't mean sitting back and drinking mojitos all day long. In fact, becoming the best you can be is hard work. Some even argue (myself included) that it'll take you an entire life, because it's a never-ending task. Trying to consistently improve yourself seems like a smart strategy in general, not just for a career. The important question to ask is not "how can I be as good or better than person X", but "how can I be a bit better today than I was yesterday". It seems like a small difference, but the effect is quite enormous.
I know I'll never be the best scientist in the world. I was never the best evolutionary biologist, never the best network scientist, not even the best digital epidemiologist. I won't be the best writer, the best blogger, the best pianist. And even though my kids tell me I'm the best dad in the world, I know I'll never be, because there are over a billion dads in the world, and surely some of them are better. And that's just fine with me, as long as I'm trying to be the best I can be. And if tomorrow, I'll try to be just a little bit better than I was today, everything will turn out all right in the end.