Hello, Steve. Ruchi makes a good point about equilibrium. However there are a couple of things I'd like to add.
Bathroom scales do not tell the whole story. Not even the better electronic ones. How so?
When you exercise large muscles, like the butt muscles, the lean muscle mass increases a bit, while the fat content of that muscle decreases a bit. The fact that you look the same, and weigh approximately the same, is irrelevant for your health.
The next time you're in the supermarket, check out the meat aisle. Some cuts of beef are leaner and redder. Other cuts are well 'marbled' with fatty streaks. Without regular walking, your butt muscles would be more marbled.
With slightly less body fat, your insulin receptor sensitivity increases a bit. (Generic aerobic work has the same effect.) This means that you are a bit healthier than you'd be without regular walking.
Walking on level ground does not do a lot for your quadriceps muscles, in the upper front thighs. I wrote a hub about Gorilla Walking, an exercise of my own invention, which isolates the quads, in addition to providing moderate aerobic work. You could do GW one day, and regular walking the next.
Gorilla Walking is best done indoors. For that reason, it's the best option for rainy days.