45 - 90 mins on the elliptical trainer
Some combination of:
Abs (lots with stability ball)
Lunges (regular and curtsy)
Funky pelvic tilt thing with one foot on stability ball, other leg in the air (awesome for hammies and glutes if done right, bye-bye lower back if done wrong!)
Wall sits (doing shoulder press at same time)
Bicep curls standing on one leg on a squishy pad
Triceps with cable
If some combination of sick two-year-old or dog intervenes (frequent), then I either do:
Break out the bomb-proof, largely metal, heavy-duty stroller we bought for Canadian winters (no pivoting front wheel, either, which is a real b*tch), load it up with 30lb kid, all his layers, sippy-cup, snacks, etc., grab ball-thrower for dog, wrap leash of 60lb dog that pulls around wrist and tromp around neighborhood for an hour or so, in strong Colorado Front Range winds. More of a workout than you'd think
Then try to fit in some combo of above exercises with dumbells while son is sleeping.
Makes me sore just thinking about it.