Researchers frequently use serum testosterone levels as a proxy of competitive drives e.g. in stereotype threat tests. Which suggests this is fixable with things like lifting weights or doing scary things like boxing, munchung almonds etc.
This matters, because it is not simply about a trick but - in my case at least - it is about everybody who seems better than me makes me feel kinda miserable, so getting more competitive is necessary for happiness / non-depression in such cases.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.