I think that is the part people who have never done it don't understand. It is not like going to 2 or 3 hour hard practice and then you go chill or hang out and do it again the next day. Then, go to class where you can wear sweat pants and slump in our seat.
It is total control 24/7 and can be a mental beat down. They have never done anything like that. And, done if for months at a time. It can't be replicated.
You don't quite understand what college football players go through during fall camp. There is no limitation on the number of hours they can put in for about a three week period to begin camp.
Their schedules are entirely controlled. They are forced to move out of their apartments. They are forced to give up their car keys and cell phones. They have absolutely no free time. They are woken up with banging on the door and have curfew and light checks each night. A typical day for those 2-3 weeks looks like this:
5:30 am: wake up calls
6:00 am - 7:00am: lift
7:00 am - 7:45 am: told what to eat and monitored for breakfast
8:00 am - 8:45 am: meetings (team and then special teams)
9:00 am - 12:00 pm: practice
12:00 pm - 12:30 pm: mandatory weight and mandatory ice tubs
12:30 pm - 1:15 pm: told what to eat and monitored for lunch
1:15 pm - 3:15 pm: nap
3:30 pm - 5:00 pm: meetings (position)
5:15 pm - 6:00 pm: told what to eat and monitored for lunch
6:00 pm - 8:00 pm: practice
8:00 pm - 8:30 pm: mandatory weight and mandatory ice tubs
8:45 pm - 9:45 pm: meetings (position)
9:45 pm - 10:00 pm: grab snack
10:00 pm - 10:15 pm: meeting (team)
10:20 pm : buses depart for dorms/apartments (all stay in the same dorms or apartments)
11:00 pm: lights off
They have 6 hours of practice or lifting. They have another nearly 3 hours of meetings. They cannot leave the football facilities at anytime until they are driven home each night at which time they arrive around 10:30 pm. They then are woken up seven hours later for the same thing day after day after day.