Trying to get the kids involved in exercise? A friend of ours gave us a great toy that also provides a workout:
Hyperdash. (No, I don't sell it!). It looks like a kid's game, and it is, but it's *incredibly* fun for adults, too.
It reminds me a bit of the shuttle runs that those of us in the 35+ age bracket had to do as part of the Presidential Physical Fitness and Social Torture Tests, but *way* more fun. The toy comes with 5 colored targets, which you spread around the area you want to cover. It also has a hand-held tool that looks a lot like a toilet plunger, but will detect when you tap the target.
The game gives you a series of instructions about which number or color target to hit and how many times. It senses when you've completed one instruction, and then gives you the next. (So, kids don't get frustrated when they fall behind.) The higher the level, the more complex the instructions. The object is to complete the "course" as fast as you can, either solo, in head-to-head competition, or in teams. The fastest time wins.
You can put the targets pretty far apart -- ours were arrayed around our yard, up to about 20 yards from each other -- to make the game into a series of short sprints. We played for an hour or so, and I was completely wiped out.
Be strong,
Kim