Keep track of your calorie count and reduce it by atleast 50 each day. You can also try do some stretching, for it will help you in reducing joint problems
I think that an overweight person with joint problems should start off just walking in the shallow end of a pool. Then swimming laps, but not intensely. As their speed increases, so should their weight loss. After they have lost most of their weight, they can continue to swim but I would recommend walking a bit at night before they go to bed.