And I've noticed something in all this walking: there's litter. I live in a pretty well-kept neighborhood, but even so, there's litter here and there -- plastic drinking cups, chip bags, beverage bottles, plastic bags, cigarette butts...
So I've decided that, since I usually have my hands free, I can do something about this, and I make it a goal to pick up at least one piece of litter in each direction on my way to and from campus. Nothing grody like cigarette butts or soggy paper bags, but a bottle or a cup or candy wrapper... It doesn't take much time, and there are a couple of trash cans on the way, and it makes me feel like I'm doing something nice for my neighborhood.