I get exhausted too! I have recently went to every other day as every day was just leaving me too fatigued during the day. I also run like a drunk. It's really not that funny, but I have to keep things in that perspective to deal with them. I am really strong for about 1.5 miles and then the balance and strength issues kick in. I stumble like mad for about the last mile. My neighbors have even commented about it. It's hilarious since they don't quite know what's causing it. They know I have MS, but like most lay people, they don't know what it all entails.
There are soooo many days that I don't want to do ANYTHING when I get home from work. Those are the days that I make myself run. I have hated it so bad that I have started out almost crying. It's funny though, those are usually the best workouts. The days when I feel really good and look forward to running usually don't work out that way. Who knows.
Anyway, I will exercise as much as I am able and will continue to do so until I'm not able. There are many in my shoes that would not. There are days when my eyes have been bad and my dizziness is in overdrive and my legs are tingling and I just almost don't see how I can do it. But then I think about a wheelchair and a bed and the other things that so many of us face and think "When I'm like that, I will kick myself in the ass for not taking advantage of EVERY opportunity to use my body." It's almost like I'm testing myself.
For me anyway, vigorous exercise is the only way my bowels work OK on their own (without laxatives and what not). I will not go for a few days and then I'll run extra hard and it's go time by the time I get back home. I know that's TMI, but hey, we all have shit like that to deal with (pun intended
Stick to it, I know you can!!!!