Chew some gum. When the flavour runs out, attach it to your shoe. After walking a bit a nice layer of gravel and debris will build on the surface, thus creating a layer between your real shoe and the pavement. This will save the longevity of your shoes.
As an added bonus, apply the gum while inside a,d this may save you the effort of a hoover-the-carpet job.
For some “data-machine” related money saving tips, visit the data-doktor.