In college I had a friend whose father was an OTR trucker. Absolutely destroyed his back. He had back problems when I first met the family and a few years later he was on medical leave and unable to work, and he was
maybe in his late 50s.
He wasn't driving for Walmart of making that kind of money then, so I hope he was able to move into a different career that didn't do further damage.
It's not a job I'd want to do. Ergonomics aside, I find driving to be very unpleasant in large doses. Having to put up with traffic, shitty drivers, weather, and everything else 8-12 hours per day is not my idea of a great time.