1. Not starting a business in grade school
    I wish I had focused on starting to learn principles of business from strategy to people management in fourth grade. The business itself probably wouldn't have been successful; it's about shaping me at that age. I'm completely serious and think it could have helped me a lot along the way.
  2. Not taking more calcium supplements
    I was never a big fan of milk and I think I have thin bones so I probably should have consumed more calcium growing up. Part of the problem is that men's supplements are often devoid of calcium (it's a mystery). Good news is I have never broken a bone.
  3. Staying in school
    This guy Dave Fetterman asked if I wanted to drop out of school and work at Facebook full-time and he was probably right. Instead, I ended up getting my degree and taking a lot of grad classes and spending time at Google and Microsoft Research, which is still pretty great by a lot of measures so I'll live.