But walking is rather easy and does not really count as demanding exercise, at least if there's almost no elevation change. Also, I only need about 12-13 minut

But walking is rather easy and does not really count as demanding exercise, at least if there's almost no elevation change. Also, I only need about 12-13 minutes for my walk to work, so I get only 25 per day - surely better than nothing but not enough to really counter work sitting at a desk 8 to 10 hours a day.