One great cause of failure is lack of concentration.
What you habitually think largely determines what you will ultimately become.
To live is to express, and to express you have to create. Creation is never merely repetition. To live is to express oneself freely in creation.
Out of chaos, find simplicity, From discord, find harmony.
Concentration is the root of all the higher abilities in man.
The martial arts are ultimately self-knowledge. A punch or a kick is not to knock the hell out of the guy in front, but to knock the hell out of your ego, your fear, or your hang-ups.