The day I can no longer crawl under the green turd.........sigh!
I feel for those who can't do things due to bodily injuries or surgeries of the past. I'm just waiting for my day to come along.
To the OP, can you try laying down on your back and then rest for a few minutes before you take the next step? A baby step, then rest?
I will say that once you have gotten your hands dirty from dealing with the gearbox, driveline, brakes, etc, the next time will be a little easier.
Had the truck's bottom side steam cleaned days after I bought it.
Mr. Steamer