Weight loss advice for new mom?

I just had my son 2 weeks ago, and I'm excited to say that I've already lost 27 lbs! (My baby was 10 lbs 4 oz at birth.) I've been breastfeeding and eating fairly healthy, but I'm holding off on exercise other than walking until at least 4 weeks post partum on my doctor's recommendation. Any advice on ways to make time for exercise once I go back to work in 4 weeks? What worked for you? I'm sure my weight loss is bound to slow down soon. FWIW, I gained about 45 lbs during pregnancy and was about 20 lbs more than I would have liked, but still at a healthy weight pre-pregnancy.