I know that if I push myself too hard, I pay later in the day.
For instance, yesterday it was in the 80s here. I had to empty some water out of my koi pond, so I used a 5 gal. bucket and made about 25 trips to empty it.
Later that afternoon, I got up to get the trash and recyclables ready to take to the curb and I could only do a small amount of it before I had to go back and sit down for a bit. Up and down,up and down...I felt heavy, like molasses; just so weak. It actually made me think for a minute that maybe I was having a heart attack, but I didn't have any chest pain or pain down the arms, in jaw, etc.
I also turned on the AC and that cooled down the warm house a bit.

There are so many things that turn our sxs on and off