On Sundays, I can hear re-aired, commercial-free versions of "Meet the Press" and other programs, so I often time my walk to coincide with these shows, which run every hour from noon till 5 p.m. And some mornings I listen to news rather than music. It gets the heart pumping and stands in for the newspaper if it's not my morning to have it.
But beyond the pace there is the tone...
Walking with talk in my head creates a conversation, one-sided for the most part (unless I blurt out a retort to a particularly egregious statement).
But walking with music in my head allows for the inner dialogue that is such a healing part of the stroll.