Same for many professions that require higher education and even the ones that seem easy on the body. People think dentistry is easy on the body because "you sit all day". No, you hold very specific and controlled positions for long periods of time while you simultaneously focus on every body/hand movement down to tiny fractions of a mm. I can bench +300 lbs, squat and deadlift +400 lbs, and walk out of the office many days feeling physically sore and exhausted. I started lifting because even in my early 30s I was starting to get chronic back and neck pain. Add in things like arthritis/back and neck pain and it gets difficult to do this into your 60s.
While I was at Universal on vacation my partner had an OR case for a 12-year-old that started at 8:30 am and ended at 5:20 pm - he stood the entire case hunched over and took one bathroom/protein bar break around 1 pm. That's hard to do even into your 50s. Thankfully, those cases are really few but they happen.
