I work at a music retailer, and I used to help deliver digital pianos and keyboards to customer's houses if the movers were overbooked, but one time while driving to a customer's house, I turned hard right and absent mindedly turned my torso and reached out with my arm to keep her digital from sliding towards me from the passenger seat, and I tweaked my back (sciatica). Of course it didn't happen while I was lifting
I couldn't stand (or even sit) up for over 2 weeks; my family Dr got sent the xRays and my Doc was like "Mark, your back looks terrible, what the heck have you been doing to it? No 35 year old should have that much mileage on his back!"
Me: Doc, I'm 49 (this was a few years ago)
Dr: Oh.
My Doc (who's been my family doctor since I was 6) forgot how old I was because I used to look young (my hair suddenly turned grey after 52... before that it was still mostly black. ANd people wonder how ObiWan is supposed to go from red headed 51 yr old Ewan McGregor to 62 yr old Alec Guiness in only 11 years (in-universe time there's only 10 years between the obi wan series and Star Wars ANH).
And I'm here to tell those people, unfortunately, that your hair really can turn mostly grey almost overnight!
It's *definitely* the mileage, yeah.
Mark