After a walk…static stretching can be very beneficial.
There’s no need to work on becoming super flexible during this time, but it is worth doing just a few minutes of stretching after each walk, when your muscles are the most warm and compliant. A three to five minute cool down is just enough time to help maintain your mobility and a healthy range of movement, and it’s likely to improve balance and postural stability, especially as your walking becomes more varied and vigorous.
Here is a link to some very good Stretches for Walking by the American Heart association.
Do some or all of these stretches slowly, never to the point of discomfort; hold each stretch for ten to fifteen slow, deep breaths. Begin each stretch standing up, and feel free to rest one hand on something for balance if necessary. If you have time, go through the cycle twice.
“If stretching were wealth, the cat would be rich.” ― African Proverb