I'm really worried about a friend of mine, he's having some serious medical issues, and it seems to be having a really big effect on him, mentally. He'll say things that used to make him happy now don't, he just feels sad. Nothing helps. Not his girlfriend, not music, not anything. I don't know what to say. I feel like I've said "I'm sorry" too often. I've told him I'll be here for him if he ever needs anything, but I don't know what else to say!