My mother is constantly grumpy every day, I'm afraid it's making me negative! What to do?

A lot of people get grumpy when they get older. I don't know why it happens. Some people have pains and problems, but always stay upbeat. Others go the route of Eeyore. It can be very painful to live with. A hard thing is that we get this feeling that if we can say the right things or do the right things, it will make the person happy. That makes us feel guilty, like we're doing something wrong. It does help to realize that we're not the cause of the person's unhappiness. That takes the burden off of us to try to make it better. Still it doesn't make being around the person any more enjoyable.