Nursing Mothers out there?

Hi just about 6 weeks postpartum and now able to start working out.... IF I can find the energy! I also have a insatiable appetite, not sure if it is from breastfeeding or from lack of sleep. I do tend to eat sweets when feeling tired. I am not sure how to control myself when I feel so exhausted. My little guy does not sleep through the night and I have a 3 1/2 year old girl to watch during the day. Love my kids to bits but motherhood is not easy! It makes it hard to find the time to take care of myself.
What do you other moms do to get that workout in or help stop the fatigue eating?