A lot of what Mark says about chess can just as easily be said about the stock market. The two are very similar games:

It has creativity, it has stamina. You control the opening, but you can't control the middle game or the end game. You don't actually know what you're going to do.

You need to be creative with your style. You need concentration. It's trying to achieve perfection. It's the best mental battle out there.

You don't get better off of playing. You get better off of studying.

You can't get around without knowing a lot of theory. If you don't study, you're just hoping.

It's not about confidence, but you can't be scared. If you're intimidated, nothing good's going to happen. You need to have strong nerves. It doesn't matter what they do, you play your game.