system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the difference between regular exercise that is healthy, and laborious excerise(manual labor etc) that causes joint/muscle issues down the road?
gpt
In a very general statement, not much. It is possible to overstrain and injure oneself during exercise just as it is possible to do so in manual labor. 

Manual labor might be more prone to be repetitive (for just a few joints/muscles), last much longer at one go, require long periods at the same posture (sitting, hunching) and not allow for sufficient recovery periods - and this has a high likelihood of causing later problems. But not all manual labor is like that. And as you recognize, not all exercise is healthy either.