Live life fully while you're here. Experience everything. Take care of yourself and your friends. Have fun, be crazy, be weird. Go out and screw up! You're going to anyway, so you might as well enjoy the process. Take the opportunity to learn from your mistakes: find the cause of your problem and eliminate it. Don't try to be perfect; just be an excellent example of being human.
If I'm diagnosed with cancer I might become despondent but someone young might not and they might need connections with somebody outside their circle of family because their family is so despondent.