When I say “walking chords”, I don’t mean you should put a leash on your chord progression and take it out for a walk. Walking chords are bridging two or more chords with a single note run that utilizes lower-pitch strings.
In outlaw country music you’ll find opportunities to “walk” from one chord to the next. This works best for I, IV, V chords, but in theory, can be done between any two chords.