Why do we get sore?
Our body/muscles get sore because our muscles can only handle so much until your muscle fibers will start to tear. The word tearing may sound offle, but when the microscopic tears happen, it rebuild new muscle after that. The tearing and rebuilding is what causes that soreness the few days after that hard workout.
But this all occurs mostly in people who don't usually work out & then do a strenuous activity or do something hard which they usually don't. The more you do strenuous activities, the less the soreness will be do to repeated cycle.