These are just a few things I started to do after I had my third baby. I would think a lot about joining a gym or sporting club but I never seemed to find any time to do it. So my housework became my workout.
Laundry: Use a low wide basket and sit it on the ground beside you under the clothesline. Don't bend over to pick clothes out of the basket, instead squat down beside it, keeping your back straight. You can average 30 or so leg squats for a decent load of toddler clothes. Keeping a peg basket on the ground helps you get even more reps.
Dishes: Put your plug in the sink and turn on the water. While waiting for the sink to fill do push ups against the counter. As my benches are quite low on me, I stand with my feet wide apart (a kind of sumo stance) and keep my glutes and abs pulled in tight. More dishes there are the more it hurts. Great incentive not to let them build up too much.
Mopping hard floors: I threw out my mop, instead I have a large car-washing sponge. Kneel on the floor and grip the sponge with both hands, sliding it as far away from yourself as you can manage comfortably, and use your abdominals to pull it back in against yourself again. (even my boys enjoy doing this one, although we usually end up having a bubble fight... lol)
Toddler Tantrum Averter: As soon as the bottom lip drops, whisk the child into your arms and bench press above your head 5-7 times, as many as you can manage (depending also upon age and size of the child). Finish with tipping child upside-down and blow large raspberry on their stomach. Averts tantrum most of the time. Not always.
There's heaps of things you can do during your usual day to burn those extra couple of calories. Housework and childcare burns calories as it is, and just doing it a little differently can help to intensify it. Anybody else got ideas on it?