Self-help when your life isn’t what you thought it would be

Okay, I’m looking for a book that can help bring some perspective. I have a friend who is hitting a mile-stone bday and their life is nothing like what they thought it would be. Theyre also in a caretaker role, and feeling very stuck. I don’t discount the very hard situation they’re in, it truly sucks but everything isn’t awful. They can’t get out of their own way, and see the good. All they can see is the bad. There is, obviously, some depression as well (lifelong battle). They’ve recently been escaping into the world of books and I’m putting together a really nice gift basket for readers and I thought I might include a self-help type of book. I’ve got lots and lots of other things in the basket too. But there are soooo many out there and I thought maybe I would get some suggestions from you all. Thank you!