I work as a mechanic at a shipping port. I work on refrigerated shipping containers, and do any work related to them - the boxes run on 440V AC electricity, and must be plugged into a power source, whether they're on a ship or on land. We have unhook/hook up the boxes when they come off and go on the ships, prepare them for trips, maintain the generators that power them on trucks, etc. It's a very physical job, and I'm outside all day, every day.
The job I'm currently doing consists of unhooking boxes for the truck drivers who come to pick them up. I spend a lot of time sitting and driving in a pickup truck. I was thinking of simple exercises to do, and I thought "Why not use the truck?" I just put it in neutral, then push/pull it around until I get tired. While pushing, I'll alternate between using my legs to push and pushing with my arms/upper body. Using my arms/upper body, I try to "explode" to push the truck away from me. When pulling the truck, I'll brace myself, then pull using my arms/upper body, almost like I'm rowing. I'll also alternate pushing and pulling, as the resistance increases since I need to stop the truck from moving and then move it in the opposite direction.
You could do this at home if you live on a quiet street, or if you have a long driveway. It helps to have a friend to steer the vehicle and provide some extra weight.