How much "fun" you have depends on (1) how difficult your course is and (2) what grades you expect to get.
I graduated with 160 hours, my course load was INSANE, I majored in Math and Physics and I was a full time athlete as well and on top of all of that I had a girlfriend...
I went out and partied 90% of my Friday and Saturday Nights
How?
Ruthless, and I mean absolutely brutal, ruthless, and merciless time management.
I estimated how long each task I had would take and I made a schedule that would make an OCD Nazi nun proud...
I broke my day into 15 minute, 30 minute, and 60 minute chunks of time. I carried my homework EVERYWHERE with me and I did my homework and or studying EVERYWHERE to include standing in line, sitting on the toilet, eating, in class during class after class...
I scheduled time I'd spend talking to my friends, family, girlfriend. If I spent a Saturday with my girlfriend, I'd have 4 or 5 hours of that day scheduled for studying. I'd do most of it while she slept or watched her favorite program or sometimes we'd do homework together as a "date".
I scheduled time I would rest and nap and do nothing.
And I absolutely LOVED getting ahead on my schedule. If I finished a task early, I'd jump right in to the next task then the next.
I would also decide how much time and effort it would take to get an A or a B or a C.
Here is an example. I was almost fluent in Spanish and I had to take 2 semesters of a foreign language. So I choose Spanish and I purposefully tanked the entrance exam so I could take Spanish 101 and 201 which would result in an Easy A for me. I had to take some hard Electrical Engineering courses and I realized that in order to get an A, I'd have to study about 10 hours per week just for that one course, but if I wanted a B I'd only have to study around 6 hours per week--so i would make the strategic choice early for the B and schedule accordingly.
I was careful to not overload myself on "hard courses" and I was very strategic in my hard course load. I would try to limit myself to no more than 3 really hard courses per semester. For instance, I made sure my hard Math Courses coincided with my hard Physics Courses in a complimentary way... in essence the overlap was such that I would get taught the same concepts in both classes so in a way I'm taking the same class twice which means I can reduce my overall study time by 25% or so based on the overlap...
and on top of all of that, I ran Track, did Boxing, was in a Martial Arts club, and Chess Club.
so yes, it is possible to go to college, have a great GPA, and party
The key is brutal crazy OCD time management as well as laser like focus in class. No day dreaming, no wasted time. Keep great notes, be brutally efficient in everything you do learning related. Once you get ahead it is easy to stay ahead.