Walking exercises different muscles in different ways. I once did week long backcountry backpack trip in the Rockies, so there was lots of ups and downs. When I got back on the bike I first felt like I had a totally different set of legs than before the trip, but the old ones reappeared relatively quickly.

BTW...That’s a lot of steps/day. On Friday I walked nearly 12,000 according to my phone. Estimate that was about 3-4 miles over the course of the day.