When I was young, I read The Richest Man in Babylon, which said to under-spend your income and invest the difference. Lo and behold, I did this and it worked. I got the idea to add a mental compound interest too, so I decided I would sell myself the best hour of the day to improving my own mind, and the world could buy the rest of the time. It sounds selfish, but it worked.

Charlie Munger on investing in your brain. The Richest Man in Babylon looks pretty sensible.