How much time should a senior over 70 spend exercising each day?

The right amount is as much as you need when you are younger than 70 years old. To sum it up, God did not create the human body to sit inactively. As you become older, you’ll need to be more cautious and undertake less intense activities, but you still require 4 – 6 hours of exercise every week.
Every day, you must use all of your muscle groups several times. So, for example, I walk at least three miles in two sessions with my two dogs, including some challenging steep stretches. I garden, clean my own house, volunteer at a food bank, pack and carry groceries, and lift weights for 45 minutes every day.
As you get older, your mental clarity and overall health heavily depend on keeping your blood circulation going.
Remember, oxygen is everything; the degree to which you are oxygenated is the degree to which you are at peak function and alertness.
Since hemoglobin carries oxygen throughout the body, please raise your heart rate to maintain maximum performance. Find some hobbies that will help you “keep it moving.”