Hurry up, you'll be dead soon.

"Great spirits have always encountered violent opposition from mediocre minds."
Albert Einstein said that. I carry around a little blue sticky note in my wallet with that written in faded pencil. I may not be the greatest spirit. I may not have the greatest ideas. And the opposition may not be the most mediocre minds. But there's always opposition.
The point is, you've got to try. New business, new career. Whatever you're going to start, start now. Think it through but don't weigh every consequence. You have to be at least a little willfully naive to try something big.
What would you do if there was no possibility of failure? Try that idea on for size. It takes fear out of the equation and puts the focus on the positive.
I just had a young art director call me. He wants to start an ad agency and wants my advice on how to do that. Sure it may be the worst time in the history of advertising if you're big an entrenched. But it may be the absolute best time for the small, creative and nimble. There's no guarantee. But it is fun (along with unnerving and sleep depriving).
I often ask people who are unhappy at they're job why they don't try something new. The reasons they give are usually pretty lame. "We are born free and live in cages" to paraphrase someone way smarter than me.
So give it a shot. They can't kill you. The worst you can do is fail. You will never lose as much money as Bernie Madoff or General Motors or MC Hammer.
There is only now. So get on with it.