I could just say "I'm pooped" and leave it at that, but that's cheating. So I guess I should say why I pooped.
I'm working. The job requires that I keep moving ... a lot.
I'm working as a Car Driver at an auto auction, and it involves moving cars from place to place as they are brought in, inspected, made ready for sale, and sold. So one is in and out of cars, in and out of the van that takes you from place to place and then picks you up once the car is spotted, and walking about to see if anyone on your team needs assistance.
This is more activity than this old body has seen in 50 years, when I got out of the Marines.
So yeah, I'm pooped. But it's a good pooped.