How can I exercise without wiping myself out because of my Multiple Sclerosis?

I have MS and I get extremely fatigued. I would like to start a mild workout routine in the morning to help me strengthen but it just kicks my butt. I get even more fatigued and my weakness is worse. I thought about doing it in the evening after the kids go to bed but I already have a hard time falling asleep (although that is what I yearn to do all the time!) :-) Just don't know where to start.