When I go to Soto Zen practice the first thing I’m required to do is to take off my shoes, look around to find where the teacher (sensi) had put his shoes, and line my up next to his and those of the rest of the members of the sangha.
The practice of having to look for the shoes is meant to put me in the moment. I can’t just toss my shoes anywhere and rush into the zendo. Instead I have to stop and think, “Woah. Here I am – in the foyer of this building – looking for shoes. Not only am I aware of having to look for the shoes, I’m aware of the environment in which the shoes exist.
I’ve noticed that looking around for litter provides a similar experience. I look around for something to pick up and in the process of looking I see my surroundings more clearly.
Picking up trash helps me be in the moment.