10k is about 13000 steps? That is a long old walk (probably approaching 1.5 hours) but I’ve done it a few times. Reckon 30-40 minutes brisk walk a day can keep you reasonably fit.
Thats about 6.25 miles. If you can walk that in under 1.5 hours that's pretty good walking speed. I walk about 4 MPH and most people complain I go to fast!