Running on the treadmill, swimming or boxing are all helpful. In this way, when you want to cross obstacles, you don't have to worry about panting.
Once your lung function reaches a high level, you must pay attention to your muscle strength. Of course, you don't need to do some very strict gravity training, because obviously, jumping over a car is much faster than pushing it off the road. You can also do routine push-pull training according to your own weight.
Tip:
When you start practicing, you'd better practice in a safer place, such as the grass, and you'd better not practice on the concrete floor.
You must warm up before parkour. This applies to all strenuous exercise-your muscles need some time to adapt to frequent reactions.
Take a water cup with you. This is very useful when you are exhausted.