When you worry, you go over the same ground endlessly and come out the same place you started. Thinking, on the other hand, makes progress from one place to another. ... The problem of life is to change worry into thinking, and anxiety into creative action.
I realized early on that success was tied to not giving up. Most people in this business gave up and went on to other things. If you simply didn't give up, you would outlast the people who came in on the bus with you.