Home gym
◊ Apparently, assuming the "cowgirl" (or "woman superior," ha ha ha) position during sex and then thrashing around for all you're worth is the equivalent of doing several hundred consecutive sit-ups. If you're also switching from forward-and-back movement to bouncing-up-and-down-so-your-breasts-bounce-prettily movement, it also exercises your quadriceps.
Do this often enough and you will start noticing results.
Under a thin layer of flab (because let's face it, folks, I am hardly scrawny), I have abs of steel.
Yes, it's true.
I've been fucking my way to fitness.