When you decide that you can skip going to the gym, because you had some sweaty, exhilirating sex, that you feel you've worked out hard enough, and have burned those calories just by banging

when you're hungover as shit after a spending a night drunk as a skunk

To have sex instead of hitting up the gym.

the act of getting pyhsical exercis from having sex

act of having sex as a workout.

To have very energetic sex, causing sore muscles the next day as if you have run a marathon.

Hyper energetic and prolonged copulation that with repetition counts as a full cardio vascular workout regime leading to increased aerobic capacity and six pack abdomen which in turn leads to more workout opportunities.....
Yummy mummy's eschew gym membership in favour of sexercising their way to health.