This is becoming an annoying trend for me lately. I go to the gym at my normal time one day ready to go all out, and as I start everything feels heavy and weights I did for multiple sets of 4 all of a sudden I can barely do for 2. At that point I usually get annoyed and leave. Next day, I come back and try the same workout, feel great and I either match what I previously accomplished the week before or I occasionally beat it.
I have been playing a lot of tennis lately, does this just mean I need to eat a lot more?
Anyone have a problem like this?