If you ask me about the one physical activity that every one of us; despite age, gender, occupation, health status, etc. should be doing, it will be walking for sure.
Walking can be done anywhere, at any pace, and during any part of the day. Nor does it require any equipment, neither are there any side effects that some vigorous exercises might have.
Just by doing 30 minutes of walk daily you can improve your cardiovascular, physical and mental health. It also aids in losing weight, gets fit, and make yourself creative!