Cheating - The risk / reward dynamic

I was reading an article the other day about why men and women end up cheating and it made me think a bit about it. For full disclosure, I've never cheated on a significant other, mainly because it seems like the risk is rarely worth the payoff - in many cases blowing up a multi-year relationship and creating a drama shit storm for a one time hookup.

I'd like to get some input from people who have successfully or unsuccessfully cheated on their significant other. If you were able to do it and get away with it, was it worth it? Do you feel bad about it even though your partner never knew? For those of you who rolled the dice and got blown up, what was the damage?

This isn't limited to wives or husbands. Anytime you cheated on a partner, long term or otherwise.