Lots of great past threads on this. Couple quick thoughts:
1) if you’re recently out of undergrad, realize that all your non medical friends who are starting regular jobs and making decent money and seem totally happy will likely hate those same jobs in a few years. Everyone thinks their first job is awesome, and their social media will make it seem like their lives are perfect while you’re grinding away learning physiology. I think this was a huge advantage as a non trad - all my friends hated their jobs and were envious of me for getting to go back to school! Don’t let the grass is greener sensation get you down too much.
2) give classes your absolutely best effort to start, then titrate to sanity. For the first few weeks/months, really go all out and study like it’s a full time job. Do way more than you think you need to. Probably the biggest mistake I see new M1s make is getting behind and having to play catch up. Try and be the top scoring student in the class at first, then see where your efforts land you. If you’re barely passing, then you’re going to need to maintain that level of effort for awhile. If you’re near the top of the class, you can decide if it’s worth the effort to stay there or whether you want to dial back a bit.
3) the one unredeemable sin in preclinical is procrastination. It will absolutely crush you, and I say that as the official king of procrastination myself. The velocity of new information is simply too high. It’s 5 days a week of new material, and there are only so many hours left for study even including weekends. It doesn’t take long to get so behind that new material doesn’t even make sense anymore. And you won’t have time to catch up.