Maintain one good friend who revels in telling you that you're full of hooey.

When you get to the top of the heap, nothing you hear is true (or, at least the whole truth). Keeping things in perspective is very, very difficult. The difficulty is directly proportional to the size of the heap you're sitting atop.

The best defense is one good, no-bullshit buddy. It can be a spouse. It can be a college roommate you talk to three times a year. But somewhere, somehow, you've got to keep in touch with reality. A person who can laugh at you -- and making you laugh at yourself. When Roman senators addressed the masses, they'd have an underling stand behind them whose sole job it was to lean over and repeat: "Remember you're mortal."

Quite simply, no matter how hard you try, no matter how "open" you are, you'll end up surrounded by "yes people." It's hard not to believe people who are repeating your own ideas. Resist the temptation.