the need for a pro to walk the course vs using carts. I took my son once 18 holes carrying our bags and walking the entire course. He was worn out be the 11th hole. To be fair it was a warm day 80 plus. However 4 rounds of 3 to 4 hours on the course is a workout. Not to mention all the swings at each hole, the swinging before tee time to get warmed up. I hike alot and even on a relatively flat course it will work your body, especially if you are doing another 18 the next day and then the next and so on.