If someone uses a fitness app to record their active commute, then they have saved money (e.g. Cycling saves a £3.20 tube).
Through integrating with these fitness apps, Monzo could see that the customer has active commuted and put that money saved into a Pot.
Nice idea, this kinda already exists using IFTTT I doubt they would bother to partner and there’s so many variables.
Edit:
As an example if you used Strava it could at the end of the work journey trigger an event and move £3.20 to your Monzo pot.
Here’s one of 1p every 10 meters
You could use Fitbit too, the possibilities are endless.