"For each hour that you're physically active, you can expect to live two hours longer."

I have no idea if that's true or not, but it's one exercise-related rule of thumb I found at RulesofThumb.org. The site's creators hope to eventually collect every rule of thumb -- which they define as somewhere between an mathematical formula and a shot in the dark -- and record it on their website. The results are sometimes helpful, often useful, and occasionally kind of funny.

For instance, consider:

• "To get a "blow" out of a stuffed-up nose, always blow the clearer nostril first."
• "If your earlobes have a diagonal crease, you may have clogged coronary arteries."
• and the unusual: "If your turds float, there's too much fat in your diet."

Check them out. You might just learn something!