Measurements (of any given period):

Subway card swipes
Trains ridden
Cellos played
Elevation Gain (based on subway steps taken)
Elevator Gain (based on flights ridden)
Money requests denied (subway or sidewalk)
Toilets used
People offended
Kindness offered
Requests turned away
Requests taken
Emails sent
Scheduled hours changed
Breaths noticed
Languages heard
........