I hear you. I haven't lifted in I don't remember how long - 5-6 years maybe. Probably that long since I've done specific cardio workouts (at least regularly), though I've been skating as a ref this whole time - it's just not the same. So when I started going to the gym again last week, I tried to take it easy with both Cardio and weights. I'm having to force myself to not push the weights or reps up (or set #s) too fast. I'm 49 now and don't recover at all like I used to. Like last night, after the elliptical, I did crunches and then wasn't feeling it on working weights, so I just called it a night, despite that nagging feeling I should continue. Listening to your body is hard when you're excited to make progress. Good news is, my skating must have kept me in reasonable cardiovascular shape, because I'm already up to 36 minutes on the elliptical.