By the time I was 10, I was running a small “colored glue” operation with my friends.

We’d shave colored pencils, separate the pigments from the wood chips, and mix the pure color dust with liquid glue to create custom shades. I sold little bags of these homemade glues for 20 to 30 cents, depending on the size. Eventually, we started asking ourselves why people really needed colored glue, and the business flopped—but the science experiment (and the fun we had) stayed with us forever.

 I still remember one of my first failed negotiations: I spent all my money on a cute toy a friend offered me in a trade, only to get bored of it a week later. Lesson learned—needs and interests evolve.