A good exercise goes a long way as it improves not only our physical well being, but also our health. One of the best way to be healthy is to be engage in sports. Parkour is a great sport, which you can do in the city. It is not a crime, but when you paint walls and do parkour then that is a crime.
The cops are coming after you since you are vandalizing the streets. Using your parkour abilities, you need to escape the op, but that won't be easy since the cop also does parkour.