I also drink a lot of water (always have). I also train Muay Thai and am in my 40s, which means an hour of 1:1 with my trainer would just leave me ridiculously tired. I started supplementing with creatine and immediately it was evident that it was working -- after 8-10 rounds on pads and the heavy bag I was fine. To the point where my trainer would often tell me to take another round on the bag.

At a certain point I was wondering if it was just placebo, stopped taking it for a month or so, and was quickly back to feeling tired after training. Started taking it again, back to feeling energized. It really does work.