Why is physically exerting yourself to the point of exhaustion at the gym good for you but various jobs involving manual labor seem to cause permanent damage in the long term?

Question

Why is physically exerting yourself to the point of exhaustion at the gym good for you but various jobs involving manual labor seem to cause permanent damage in the long term?

In: Biology

Answer 1

1 or 2 hours a day are spent in the gym by gym rats, but 8 hours+ per day are spent on the job, without long resting periods. Spending 40-60 hours in the gym and not stopping for exhaustion or injury is also going to cause damage.