You notice that it is getting harder to walk as you get older. What should you do? As often the case the answer is "it depends". Finding a time and place to practice walking is the most important part of keeping your walking going but that is only part of the answer.
Alva asked recently where to get a walker for her to practice her walking safely. There is a place near San Jose called AbleCloset a not for profit organization with walkers to borrow for up to six months. You can look at the website and find out if they have a walker that would fit you.
Another place to keep on walking is on the treadmill with both hands supported or with a support walker that lifts you. This lifting is done with a device called a gait trainer or with the treadmill itself. Alter G is a company building treadmills with a support system designed to lift you up ever so gently to allow you to walk with less pressure on your feet. UCSF in San Francisco has a couple of these treadmills in their running clinic and one in the fitness center.
The very cheapest way to practice walking without too much pressure on your legs is by going in the water as Nano is showing on this picture. The pool is the best place to walk in the water. Gravity eliminated will both make it easier to balance and easier to walk. The Janet Pomeroy Center in San Francisco has therapeutic hours for adults and youth.