Mark's gives his advice for people to dream big in his newest book, Jump In! Even If You Don't Know How to Swim.
"Most people don't do things from fear, and they want to have a hundred percent of things figured out before they get married, change boyfriends, change jobs," he says. "But you know what? Nothing's perfect. You can't be a hundred percent certain. You must be willing to jump in with half the facts even if you can't swim. You'll figure it out. And that's how you make it."