I try to get at least 10,000 steps in every day. Walking helps me slow down, process my thoughts, and soak in the essence of the world around me. This can easily be done no matter how urban, suburban, or rural your environment is, and it's worth doing even if it elicits strange looks from people in car-centric areas. In fact, observing small details in a seemingly mundane environment can be spiritually awakening, attuning you to the beauty that exists everywhere.
Walking spurs creativity by reducing activity in the brain's default mode network (the part of you that's overly inward and judgmental) and by providing a much-needed break from the overstimulation of work, responsibilities, and the internet. Being outside puts everything into perspective - your sense of physical space, the passage of time, identity, life goals. It teaches you to think of every moment not as a utility function but as something to experience and be aware of. Insights flow naturally from this state of being, rather than having to be forced out of your brain through intense concentration.
See also: Wu wei, Simplicity