Koa Kimura, my first teacher's teacher told us if we did the breathing practice for onehalf hour every day for three years in a row (never missing a day-if you did, start over) there is no need to practice a martial art, you would have such power that no one could touch you. 

  Every day sit quietly, back straight, and breath mindfully, slowly in and out (of course) focusing your breath into your center, breathing to and from this center.  Start with just a few minutes each day and let your practice grow.  Don't force it, soon the breath breathes you, soon there is only the breathing."

"  Aikido’s attraction for me has been its ability to challenge and engage on three important levels; the body, the mind, and the spirit.  To be a good Aikido practitioner, all three must be trained and honed.  I know of no other activity that does this so well.  Also, I have traveled and trained in different parts of the world and greatly enjoy the camaraderie of Aikido followers.  No matter where, I have found people who attend Aikido dojos are quality individuals.
  Aikido has improved me by training on the three levels just mentioned.  This has turned out to be an incredible stress reliever in today’s hectic lifestyle.  I can apply Principles of Aikido in personal and business relations, e.g. blending and merging with a strong event/personality to exert a high degree of control rather than brute confrontation."

How long do you have to train? Many people have asked me, "How many years do I have to practice zazen?" And I answer, "Until you die." They are not very happy with that answer. In the West people want to learn fast; some people think once is enough. "I came once and I understood," they say.

But the dojo is not like the university.
In Budo, too, you have to practice until you die.