Dave, I loved your latest e-mail regarding HIIT! I think I'm nailing it in another way - let me explain...

I'm 61 years young. I'm pretty lousy on my feet, but something magical happens when you put me on a road bike. I'm still good for about 20 miles, more or less, including hill climbing. I only do it on Mondays, because that's when my friends can do it. It also takes the rest of the week to recover.

Tuesday and Thursday, I do Pilates at a somewhat local (I live 45 minutes from anything, here in the S'Cruz mountains) Club Pilates studio. My muscles fatigue fairly quickly there, but it's getting better, and the instructors usually move to different muscle groups after a few reps, so that's good. My instructors know I have MS, and when my muscles spasm (which is often), I just relax until things settle down. The movement isn't necessarily HIIT style. Most of it is slow and deliberate.... and killer! I still hit the wall by 4 pm with fatigue, but I'm not gonna kick myself. I can get a lot done by then.

Thing is, both of these activities are done in a group setting. If I don't show up, people wonder what's up. Working in a group is very motivating. I have no interest in trying to keep up with the fittest ones on the road, or in the studio. I'm doing this strictly for myself.

For me, exercise puts me in my happy place. I'm prone to depression, and exercise works a charm every time! My cog-fog goes along with my fatigue, and exercise helps with that, too, but like I said, by 4 pm, I'm done!

Any kind of emotional stress or "putting me on the spot" nullifies even the best benefits exercise can give me. I can't think, find words, move well, and I wet my trousers all at the same time. OTOH, while I'm exercising, emotional stress just goes away!

Just my $0.02. YMMV