Sex is my favorite form of exercise because you don't have to get dressed and go to the gym, and then fight over your favorite cardio machine. All gyms have those people who hog the good machines, and the one at my gym wears full make up and drives a miniature hummer. Every day she manages to get there 5 minutes before I do, she goes at a snails pace, and wears full make up...ugh.
As far as a regimen? I like to have sex a couple times a week. I mean its like pilates, you know you can have short sessions several times a week, or you can have like the 75 minute master session on tuesdays and thursdays, and just do some light cardio and stretching on your off days.
Lets all admit it, it goes by a lot quicker and is far less boring that running on a treadmill.