I wasn't in construction but I did spend three years working as an arborist / forester between 2022 and 2025 whilst taking a little break from tech after a long 20-year stint. I've been in good shape since I was 30 with strength training, cardio and even a little stint as a masters level competitive olympic weightlifter. A long way of saying, I know my body fairly well.
Two years into climbing trees in domestic settings and hand cutting in timber plantations, even three days a week and my body was hammered. Now maybe that's because I was in the 46–50 year old range, but it was clear it wasn't a viable long-term strategy for me. Speaking about the people I now know in that industry, it's commonplace for "climbers" to be done by their mid-thirties. Shoulders all mashed up from climbing and carrying heavy loads. It's not pretty.
On the positive side and injuries notwithstanding (I did get a shoulder issue just like everyone else) my bodyweight dropped 10kg and I did look (and feel) much nimbler. The core of the problem in this kind of work is that when the rubber hits the road "getting the job done" always comes before "correct techniques for doing X". And there's no liability claim to be had as at the start of each job you sign the risk assessment which states that you will get it done in a health-and-safety-compliant way. If you don't sign, you're not on the crew the next day and you're walking home from site. This is basically how it is in the UK for these kinds of jobs where salaries are between £24–34K annually.