Running and walking work the same muscle groups, with very similar health benefits as well. The key difference is the intensity of the workout; it takes more time to burn the same amount of calories when walking vs running.
If you are moving from a sedentary lifestyle to a more active one, walking will be a bit easier and you’ll improve your cardio fitness slowly and steadily. Walking is low-impact activity compared to running, making it easier on your bones and joints, which is a real benefit for older or heavier bodies.
Walking requires more time to produce the same results as running, so you can always break up that time into shorter, more frequent walks (ie 3 x 10 minutes vs 1 @ 30 mins).
Also see West End Wellness Walks