I wasn’t kidding when I said marriage and kids age you. I think the trend toward marrying older and having fewer kids has a lot to do with people staying youngish longer.
I have one child, and I had him when I was 38. Right before I got pregnant, I still looked about 30, 31. By the time my son was 2, I had aged about 5 years.
My mother had just two kids, which was a small family for my time, and she had them relatively late-- not very, just slightly. She was 27 when I was born, and 32 when my brother was born. She looked her age when she was younger, but she aged slowly, and by the time she was 70, she could have passed for 58. Then she got cancer, and the chemo aged her fast. But before then, she looked really young.
I also wonder if the reason a lot of people in Hollywood looked much younger than the typical US adult from the start of cinema until recently (when the general public has closed the gap quite a lot) is that Hollywood performers, especially women, have tended to have many fewer children, and the really famous ones have been able to hire nannies, and send the kids to boarding schools.
Your point is well-taken about physical labor aging you, but I suspect even that has eased somewhat, because things like workman’s comp and short-term disability, have forced employers to train employees to “work smarter.” When I was an interpreter, I was in a lot of different workplaces, and I saw supervisors call out employees for lifting incorrectly-- ie, through the back, not the legs, and soforth. People wear lifting belts, and while they are not exactly treated like princes, they get better care now than they used to. People get care for injuries on the spot, and get time off, because employers know that giving a little now saves them a lot later-- it’s less about caring, than about what saves money in the long run, but it does make people’s lives better.
Even among the hardest working, 50 is still the new 40. Maybe not the new 30, like it is among the middle and upper classes, but still, there have been gains for everyone.