More and more evidence points to the importance of regular physical activity to stay healthy. One reason pepole have a total hip replacement is to reduce pain. This usually leads to an increase in their activity level.
There's also quite a bit of evidence to support the benefits of exercise for anyone with osteoarthritis. Fort the sake of all your joints, exercise is a good preventive activity.
Just being aware of the change in your focus and motivation is a good place to start. It may be helpful to join an exercise group to get you moving more. Or perhaps there's a friend who would be willing to join you on walks. Many communitities have a mall walking program. Or look for an aquatics exercise program at your local YMCA or other health/fitness club.
Try to add one minute of exercise or activity to each day -- even if it's just walking around the block. By the end of a month, you will be up to 30 minutes each day. The goal is to exercise at a moderate intensity 30 minutes daily, five to seven times a week.