When something doesn't go exactly to plan, money is tight or a business is struggling - see it as a challenge rather than a failure. Look outside the box and try and find a solution - you'll be surprised how many great opportunities and possibilities arise when things look bad. You've just got to open your mind and not be afraid of sticking your neck out!
If you are seizing on a new business opportunity, deliberately move your customers' expectations up a few notches and consistently over-deliver on your promises - you will leave your competitors struggling to catch up.
I think great businessmen are more likely made than born. I don't know if it's from your upbringing, your parental background, the struggles you go through. In my own particular situation, I left school at 15 and I was struggling to survive in the jungle and that was a great education. So I think just getting out there, hands on, learning to survive teaches you a lot.