Honestly I am living a MORE balanced life right now in med school than I was in undergrad (although I'm only ~2 months into M1), and I'd even say I did a great job of hanging out with my friends and keeping up several hobbies during undergrad (as in I have no regrets about how I handled my social life in college... only wished I exercised more regularly but I'm on my way to fixing that in med school!)
I am serious that you have the time to have fun, and you SHOULD be having fun. Premed is hard, but it shouldn't be consuming your life to the point that you don't know how to have fun. It's true that free time will not fall into your lap and you need to make the time for yourself, but it's completely doable with time management and accepting that sometimes you need to take a step back for your own mental health.