I could start this off with a quote by Peter Pan, but since I've never seen the movie I'll probably screw that up. So instead I'll start it like this.
I have a friend who is scared. He is scared of the real world and of what it means to start living in it. To deal with this fear, he has made a choice, and that choice is to grow up. I know a lot of people can relate to him since there are a lot of cliche posts on social media about how teenagers are expected to grow up too fast, so I thought I could offer some encouragement (because I'm such a caring and thoughtful person).
For my friend, growing up means acting more mature, not doing crazy things for the sake of doing them, not being as open as he used to be. While those could all be great things for safety and adulting purposes, they're not so great for friendships based around doing crazy stuff.
So to my 19-year-old friend who is now acting like he's 45, stop.
You don't have to grow up so fast.
You can still take risks, and you should while you can.
I'm sick of seeing you frown all the time.
Growing up isn't worth it, at least not yet.
Think about it this way: you only have a limited amount of time in which you are completely free. You have plenty of time during the rest of your life to go to bed before ten, grumble about your back pain, and plan out the rest of your life. Heck, that's what your 30s are for.
Right now, you should be focused on following your dreams because that is what youth should be about.
So keep focusing on the good things that have happened to you and the good people in your life. It shouldn't be hard since it's what you did last year and the years before.
Smile again, and stop worrying. Chances are, you're going to be alive for quite a while, and chances are you'll always have help if you need it to get back on your feet. Don't worry about what the future holds for you. Trust your future self and your future friends and future family and future robot minions.
The universe will provide for you, so just chill, and don't forget to have a good time whilst chilling. Don't ever feel like you're alone because we're all here for you now and not even something really stupid is going to screw up our friendship later.
Keep being rad.
Love you, bro.