For a several years I exercised religiously six days per week and often got those really tired nights. I was OK, as long as I could just lie in the recliner and watch TV -- is that what you mean by really tired?

I decided I was overdoing it, and cut down to about four days per week. I now have fewer of those nights, and I think they are related to juxtaposed workouts.

But they are still a little mysterious to me. Sometimes I can ride 60 miles and not be tired, other times no exercise and tired.

Is it just "getting old" (age 59) or is there something wrong with me?