7. Don't grow old too fast.

When New York magazine interviewed Dr. Zuckerberg, the reporter described him like this:

... short and densely built, with soft almond eyes and a stare he often holds one beat too long, as if he is attempting to stare directly through you. Despite his bald pate, the 57-year-old is notably youthful. He is wearing a blue button-down tucked into Calvin Klein jeans, a thick leather belt, and a smart pair of loafers. A gold medallion of a triggerfish is nestled in the collar of his shirt.

The word that jumps out at me is "youthful." No matter how old you are, model the idea of living for your kids, and refuse to give in to old age.