What are some good examples of rationality as "systematized winning"? E.g. a personal example of someone who practices rationality systematically for a long time, and there are good reasons to think doing that has substantially improved their life.

It's easy to name a lot of famous examples where irrationally has caused harm. I'm looking for the opposite. Ideally, some stories that could interest intelligent, but practically minded people who have no previous exposure to the LW memeplex.