Depending on the person, just saying it may be enough!

But other than that, treating them to their favorite meal, finding their favorite way to relax and letting them enjoy that, going on a trip together to the Near Shore kind of like a vacation...

Sometimes it's not just one thing either. Some people like little things over time. If you know their favorite treat like a chocolate chip cookie, it may not be a lot to give them one cookie, but finding days when they're feeling down and remembering they really like cookies can show you care - because you remembered them!