I have heard that. When I was at DHL it was much different then it is now. I would leave with 90 -100 stops and run 100 plus miles per day. I would see 4 different UPS drivers in my delivery area.
I started at 47yo. Preload for 6 weeks, then won a utility bid. Coming up on my BIG raise.
It was very tough to start, my body hated me. My body still hates me, but in different spots.
The best advice I can give you, that no one gave me is this... 9.5 list for your whole career. It might be possible to make it to 20 years at 67 with 9.5 for 10 months a year.