Kids are young enough that you can't leave the house? DH and I started a couch to 5K together, but kids are 8+ so we can do it after work while they start homework (we're gone for 30 min, jogging around our neighborhood, and have our cell phones with us).
If you can't leave them like that, I'd get a set of hand weights and set up a workout routine with those and lunges / squats / body weight exercises.