Hi, isadora. I think it's hard to get others to feel better, especially when they feel sad because it's them that are feeling sad and that's for their own internal reasons so we can't get in there and help very much.

Do you know if something happened recently, with his parents or other family or friends that got him down? I would just be a cheerful as I could (not fake though) around him and let him know you'd be happy to listen if he wants to talk; if you know of some activities he likes, suggest doing some of them together?