Running and Walking are great ways to improve many aspects of personal health. With regular practice you can improve/maintain; breathing, resting heart rate, endurance, strength, power and speed.
As we age our posture tends to get worse. Looking down, rounded shoulders, heel striking, dragging or shuffling, duck feet and much more. The result is usually painful joints or areas making you either give up or carry on in pain until so painful you have to give up.
Consider if you are using the wrong muscles or they are not strong enough to support your joints then pain will be the result.
With corrective changes by observed and practical coaching posture and joint pain can be significantly improved or eradicated.