When I was working out today I felt like I had no energy to do anything. I was on the treadmill and I usually feel full of energy and do it about 60-80 minutes without any problems. Today, I was getting tired too quickly and had to slow down a lot. However I did complete 60 minutes but I didn't burn as much as calories I used to burn.
I had ate good and I don't feel sick.
I wonder what was wrong? Should I drink something before I start working out?
Dehydration can certainly zap your energy so that might be a piece of the puzzle. Where are you in your cycle? I notice a change in energy level some months with that. Could just be an off day...how's your stress level? I wouldn't worry too much unless it keeps up. Maybe try to get a little extra sleep the next couple of days.