I'm not working full time right now, but I'll offer some of my solutions and you can adapt them to fit your life. Work on building muscle by doing training with free weights. Particularly - working with weights you can do your workout in small segments of 5 or 10 min. For instance this morning I did my biceps, triceps, and shoulders in 5-10 min. Then she wanted up.
Many gyms have child care which is open while aerobics is being taught.
Play with your kids, take walks with them and your husband. If you ever have time to watch TV, do it with your weights in hand and get a workout, or do aerobic movement like a basic side step while watching. If you have a semiprivate office space you can do isometrics or have a set of 3-lb weights and do some exercise as a short break every hour or so.