The Reid writes:

my run will exercise my heart, lungs and muscles *way beyond*
what a walk can do ...

And it will put a hundred times more wear and tear on your joints and
bones. But that's your choice.

There is a down side of potential injuries but balance
the risk of say a bit of tendonitus or a pulled muscle with a
heart attack.

Walking is very effective for maintaining a healthy heart.

--
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