Tough is a relative word. I worked as a construction safety officer in a petroleum refinery. In construction there are mainly some types of hazard you need to take care of. Like fall from height,confined space etc. As there are frequent changes of workmen are involved,likelihood of accident is very high. You need to train them and watch their job thoroughly. So there will be very much physical activities and note that most of construction companies have a minimum of 12 hrs working shift.If you want to start your career as a safety officer then construction is fine. But try to get into a manufacturing farm in future otherwise your social life will be sucked due to long hrs and frequent movement.All the best for you future.