Dance parties. I am out of breath a couple minutes into our dress up/dance parties. Just find some tunes that make you want to shake your booty and swing your kids around. You can turn dance party into extreme squat sessions.
Trail running. I take my kids to nature/hiking trails and chase them around pretending to be a monster, or fairy or dinosaur. It's so much more pleasant than walking on roads because they don't have to hold hands and they get to run themselves ragged as well.
Interpretive walking, follow the leader or jump, jump, jumping jacks, walk like a ______(frog, bird, dinosaur) make walking (indoor or outdoor) a lot more fun for my kids. When they are doddling or refuse to walk we make it into a game (well, when Mom is up for it) and it turns out we get to where we are going much more quickly and with many more giggles. When I don't have the motivation or patience for a game like that I put the little one in a backpack (ergo baby is comfy) and then have my eldest hold my hand and we speed walk. Carrying 30 lbs on your back for an hour is a pretty good workout.
Indoor games like: Mama swings you around and around, lifts you up and drops you down, gymnastics, hide and seek, how fast/high can you jump, airplane, etc.
Cleaning - with gusto. Gets the job done in a hurry and burns a couple of calories.