I found an old pedometer the other day and put it on just out of interest, to see how active I am on an average day. I believe you're supposed to aim for 10,000 steps a day to be healthy. Quite startling results - on the days when I'm childminding, I average around 24,000 steps, which is the equivalent of walking about 10 miles. It's not like I'm taking them on long walks or anything, just the school/nursery run & trips to the park which isn't far away. It must be just that I never seem to get the chance to sit down!
Definitely a career worth considering if you want to get fit...