No time for exercise? You may already be exercising more than you think.
Clip a pedometer to your waistband when you get up in the morning. You'll be amazed by how many steps you take on an average day chasing the kid(s) around. Write down your total steps at the end of the day. After a week, add the totals and divide by 7 to get your daily average. Once you know your average, you can start trying to increase it a little at a time with such simple changes as looking for parking spaces further from the door. A mile is approximately equal to 2000 steps. Increasing your daily average by 300 steps every week would add a little over a mile per week to your walking activity. The results will be good for you and your kid(s).