Here's a radical idea—getting fit is fun and contagious

What is your dangerous idea? This intriguing question is the subject of a collection of essays, edited by John Brockman, by some of the smartest people on the planet. When exposed to the innovative thinking in the essays, I remind myself that ideas considered radical, even heretical, in one century may be widely accepted in the next.

So, what's my dangerously radical idea? ...