From the interview:
Everybody’s got five minutes, nobody is so busy that they can’t do five minutes of meditation. I saw benefits right away, chief among them, I was able to focus on what’s going on right now instead of being lost in memories of the past and fantasies about the future.
When asked why meditation only makes you only 10 % happier, Harris adds:
It’s slightly tongue in cheek, but anybody on Wall Street will tell you 10 % is a pretty good return on investment, and athletes will tell you, if you can be 10 % more clear and more energetic, you win.