Further, they let that movement bleed into every moment of their day – playing with architecture they encounter as they walk, experimenting with new movements while relaxing in the park, even just walking a whole lot more to explore their environment and find good training spots. Parkour is a true movement culture, one of the very very few found in modern industrialised societies.
The key to developing all areas of the body equally and therefore to be holistically healthy is to use your body equally and as a whole: Just running, no – unnatural. Just lifting, unnatural. Just climbing, just crawling, just jumping, just playing squash. By themselves, any one of these will promote unnatural and unhealthy development. But blend all together, combine all these movements and forms of loading the body into holistic movement patterns that require constant adaptation and variation and you’re getting close to how we evolved this amazingly capable physical form in the first place.