No one feels at peak energy levels for EVERY WORKOUT...at least nobody I've ever met. Expect high energy days, followed by I can barely walk a mile days...I guess it's hormones, etc. and all other kinds of fluctuations in our body. No worries...just make sure to push yourself each and every workout. Don't be discouraged if you can't do today what you did yesterday. That's just how it goes.
Remember...it's not HOW MUCH to do in ONE workout...it's how MANY DAYS you do it....it's those of us that hang in for the long haul, consistent in our efforts that attain success and reach our goals. Much success to you!