honestly my biggest piece of advice in life might be to create a life that is sustainable. not just in an environmental sense, though that too (as much as you can anyway), but in your day to day life and choices. for example:
have more than one friend group so that if one is going through a rough patch for whatever reason you have other people to hang out, discuss, and regulate with till shit gets back to normal. do different activities with different people. meet different people through doing new/different things. find people who also enjoy your various hobbies. cultivate biweekly / monthly / daily hangouts and catch ups depending on everyone's availability and interest. i have some friends i talk to every week or day, and friends i see in person at least once a month.
if/when you don't like or respect someone, do you still reflect an inherent dignity back towards them? when you end relationships (exes, family members, friends, etc), do you do so in a manner than honours the relationships you want to keep? ie. if you or your ex break up with each other, and then you burn all their stuff over giving it back to them, are your friends really going to feel like they can safely lend you stuff without you potentially destroying their stuff if you get pissed off and/or you or them choose to end the friendship too? would you (within reason) keep a secret someone entrusted you with even if it was from someone you didn't like? (hi, me in first grade with a girl who'd only ever been mostly mean to me.) etc. do your best to be someone who is always a good friend, and barring that, a good person.
you don't have to love your job, but if you consistently feel like you don't have enough energy or time when you get home, it's at the very least a sign you should look for a new job if not a sign of rapidly approaching burnout. post-graduate me was really struggling to balance school and work at the same time but felt in my bones the issue wasn't the amount of hours at hand but that what i was doing was so draining i was losing my mind; quitting and/or finding something better is possible and rejuvenating.
have hobbies and games you can play without anyone else. download apps you can play against. read books or articles. make some kind of art or something with your hands. if you get bored of what you're doing, try something new. read a new genre you don't usually or watch a movie you've been meaning to see for forever. one of my friends is really enjoying muay thai; i've done fencing and i've been drawing every day for the past two months and am steadily figuring out new things every week.
eat food that makes you feel good about eating it, both in fullness and in attitude towards it. i try to have at least one snack a day and i have a dessert every day no matter what. often times my snack ends up being healthy but not always, and either way it keeps me from feeling hungry or too full.
all of the above also makes it easier to have at least one thing to look forward to every day. for example, every day i look forward to gaming and/or watching something with my partner, working on whatever writing project i enjoy, chatting with my friends over call, queuing up videos i'll enjoy or find interesting, drawing, and my dessert. bonus things include a weekly movie night, yummy meals, planning a group hangout once a month and what we're going to do (ren faire, board game night, cozy holiday party, etc), and any other thing you enjoy doing.
you can build a life you truly enjoy that also feels solid and secure, and it's beautiful, tbh.