These are some important articles to read. They aren't for parkour, they are for athletes in general and should be read thoroughly. Maybe if you disagree with something, you don't have to change. But at least read them and take them into consideration because they ROCK!!!

Energy Body – Learn how your internal energy works.

Mindfulness/Meditation – Great thread on APK, read through it all.

Power of Words – Everything you say or think affects you. 

Water, The Magic Potion – You should drink water water water waterrrrrr!

Thought Control – Skip down to Lecture 3.1 Thought Control – VERY good practice

Conquering the Mid-Day Crisis