Given how many people I see making the choice of being mediocre--and I say this from an elite university--I would second rwallace. Without wanting to become stronger you lose much of the incentive to be truly rational. Tsuyoku Naritai should be the first thing in your book.
Followup to: The Most Frequently Useful Thing
What's the number one thing that goes into a book on rationality, which would make you buy a copy of that book for a friend? We can, of course, talk about all the ways that the rationality of the Distant World At Large needs to be improved. But in this case - I think the more useful data might be the Near question, "With respect to the people I actually know, what do I want to see in that book, so that I can give the book to them to explain it?"
(And again, please think of your own answer-component before reading others' comments.)