Try taking 10 minutes in the morning, afternoon and evening to do some form of activity. This can include 10 minutes of body weight exercises (push-ups, crunches, lunges, squats, etc.) in the morning, a 10-minute brisk walk during your lunch break at work and 10 minutes of yoga-inspired stretching in the evening.
Thirty minutes will fly by if you get the kids engaged in something that they, too, can enjoy. Grab the family and head out for a walk, game of tag or bike ride.