I've been working out for 6-7 months now, a mix of cardio, yoga, and weights. I've noticed that it's getting harder to do the same sets lately. For example, I've been doing 170 on the lat pull-down for a couple months now, but my reps are starting to go down- I just can't do as many. I'm working on the 100 push-up challenge, and in my second week, again, I can't do as many. I'm sleeping and eating well, although I am running a calorie deficit to lose weight (which has also stopped). I feel great- just not as strong. Any ideas?