Exhaustion

[AngryOldDem]

3. Your workouts may be too strenuous.

But there could be a lot of other reasons too, like lack of certain vitamins or minerals -- your body may not be fully equipped to keep up with your level of activity.

I'd talk to your trainer about this since he/she knows your fitness level, progress, physical stats, etc.

And yes, I have experienced feelings of tiredness after exercise. Again, I think it's me trying to do too much too soon. Right now I'm trying to self-train for a half-marathon next year, and I'm trying to follow a plan that perhaps may not be all that suitable for someone my age (51). Some days I feel great (like today); other days I'm lucky to run 3 miles before I feel like I'm on the edge of collapse (like Sunday). I'm going to tweak it to give myself at least one more day of rest. So, no, you're not alone here.

Sorry I can't offer more than this...