Sensei:  You are strong, but you are only physically strong.  Physical strength is easily overcome.  Someone who is stronger overcomes it.  It is even more easily overcome by circumstances of reality that may make such strength irrelevant.  Under certain circumstances, circumstances pertaining to the environment, to your state of readiness, to your overall wellness, someone who is much weaker than you will easily overpower you. 

Deshi:  Then what should I do?  Is not martial prowess important in our training?

Sensei: Do not stop at the martial prowess of Aikido, and do not get stuck in the physical improvements of Aikido.  To stop there is to stop prematurely in one’s understanding of the art.  Rather, use the understanding of martial prowess that you have gained to understand the prowess of the fully cultivated spirit.  Press on in your practice so that you can reconcile fully both martial and spiritual prowess.  When you do this, you will know what real strength truly is.