What do you say to an unwell person?

I have a friend who has been ill for a very long time and I always don't know what to say to her coz i suck at talking in general and I dont really know much about chronic pain .. :-0 I dont have any close friend or family member whos been ill for long either. I mean its so lucky that I happen to have lived a life not knowing too much about it in a way. But I feel bad not saying much to her either. Hmm. I don't think anything I say would comfort her at all coz its not something that can be helped by words..? But if you have experience with long term pain, what do u think was nice to hear? Or if you have a sick friend, what do you guys say to them?