Something about this makes me a little sad: here's an article on how your kids can get cardio exercise. I just hate that we think of it as "cardio" now, it sounds so freaky fitness. Of course the suggestions are real simple: soccer, dance, swimming, physical video games (don't knock 'em till you've tried 'em,) jump rope, tennis, hacky sack...
Wait a minute--hacky sack? Do you really want your kid to grow up to be one of those people in the park who whacks around a teeny rasta-colored bean bag all damn day, recycling old expressions like, "far out" and unable to find gainful employment because they are too busy groovin' on Phish?
Yes, I'm kidding, so back off all you rabid hacky sackers. No need to hate in comments over a little joke. Dude, I went to UC Santa Cruz for a whole year.
Anyhow, I'll add a few more "cardio" tips to the mix. Tag, kickball, hopscotch, martial arts, walking a big, eager dog, and frisbee with bad aim. Or you can try two of my favorites for younger kids. One, say, "Can you walk like a bear? Can you move like a monkey? Can you jump like a frog?" and so on. Two, "Okay, sweetie, how fast can you run to that pole over there?...Whoa, are you back already? Okay, how about the one just past that?" Though we never considered it cardio, we thought of it as, "please dear god, let her get tired enough that she actually falls asleep before ten tonight."