It’s only natural that someone won’t be feeling their best after surgery. You don’t need to feel the complete burden of lifting their spirits – they may need a few days of rest before they begin feeling better physically and emotionally.
Meanwhile, you can simply be there with them. Bring them food, drinks, or other things they can’t reach easily. Do small tasks to make their life easier. Play games or talk with them to keep them entertained. Offer to make a meal for their family to take that burden off. Most importantly, be their friend and listen to them when they want to talk.