Well, when DH and I first started dating back in 2005 I didn't eat as much and sex was my only exercise (and there was a lot of it) and I lost about 20 pounds in the first six months of the relationship.

Actually, lost from almost 170 down to about 135, but didn't maintain it and went back up to close to 150. Maintained the 'sexercise' in abundance, mind you, just didn't maintain the not eating as much.
Sex is definitely a part of my daily plan, but as a supplement to fitness rather than a planned part of the program.

I'm with the others who don't want to find themselves planning out the activities... "Okay, I need 30 minutes tonight, up on my hands and knees would be good because I need some upper arm work right now", etc. I think that might be distracting to me.
I do target some of my other exercises to enhance the sex life as well - some ab exercises and yoga really enhance the intimate activities! And, when everyone is hale and healthy my target is daily sexual activity, so definitely part of my long term life plans.
