If you are overweight by more than 20 kg, prefer cycling or swimming over running as they put less stress on your hips and knees.

Running is a high impact exercise which puts a lot of stress on your joints. Being overweight increases this stress further, putting you at increased risk of osteoarthritis by accelerating the breakdown of joint cartilage. Also, many overweight people have joint weaknesses in the ankles, knees and/or hips that may be exacerbated by running.