Answer :
Over worked and needs rest. Lay him down on a soft surface with head elevated with his body and give him lots of water because he could've gone through heat stroke or over working the body which could lead to fatigue
He needed to stop and have some breaks because if you immediately keep working for hours, you get tired. It is a bad thing to do when your working for 2 hours straight with no breaks
I hope this solved your question
I hope this solved your question