Pilgrimage to Forgotten Art
With creating markers in one area you could encourage people to make small or big pilgrimages. They don’t need no superstitious justification to provide the advantages of a classic pilgrimage. Those are within others: to reflect over physical exercise, see new places, eventually meet people or to master a challenge. You could even just reuse existing land marks as corner points. Interesting landmarks are art pieces which are present in nearly every city but have no function and can easily be overseen. With creating routes in between them you could achieve surprising routes pretty randomly and give new live and appreciation to the forgotten art pieces or other landmarks.