Navydad17, you ARE kept busy, especially during your first year. As a plebe (freshman), you have morning workouts, formation, breakfast, four class periods, formation, lunch, two afternoon classes, sports period, formation, dinner, then mandatory study hour (for completing homework) at 8 PM. Plebes have to be in bed at 11 and upperclass don't have a bedtime. However, the professors constantly stress that they are available for extra help outside of class time and there are plenty of resources if you're struggling in a particular subject.
As for my high school information, I maintained between a 3.5-3.8 GPA in high school. Here at USNA, I had a rocky start, finishing Plebe year with a 1.7 (due to my refusal to ask for help). However, I quickly realized what I had to do, sought the help that I needed, and I now have a 3.3 GPA and have made the Commandant's List twice