Yes, it is. But it's quite a lot more exercise than most humans are going to engage in.
I spent a few years walking several hours a day. I was unemployed and homeless at the time.
It was very beneficial to my health, but I hesitate to "recommend" it because I know what most people will tell me: they can't spend that kind of time walking every day, even if it could potentially save their life.
It's incredibly distracting, I couldn't imagine trying to work on a treadmill, I can't even manage to play turn based RPGs on the treadmill on the lowest setting. The only treadmill activities that have worked for me are TV and podcasts.
I spent a few years walking several hours a day. I was unemployed and homeless at the time.
It was very beneficial to my health, but I hesitate to "recommend" it because I know what most people will tell me: they can't spend that kind of time walking every day, even if it could potentially save their life.