Someone on the Kendo World forum asked about doing kendo as a way of "self-improvement", here was my comment:
Self-improvement wasn't a goal for me before starting kendo. I started kendo because of my long-time fascination of it and, in general, martial arts. But to perfect my kendo I find it necessary to adjust many of my attitudes, those that you use to face daily events and people. It has strengthen my mind, helping me to deal with stress better. It also makes me aware of the importance of having a good basics when learning something new, and that means being humble and self-critical.
I view the unhappy experiences in the dojo as a teaching in itself too. Which happen very often in real life, which you can't turn yourself away. You just have to learn to deal with them.
All in all, on the road to achieve the perfect command of the sword and the body, one learns many things and adujsts oneself from outside and within. As a consequence, he/she adapts to difficult and unexpected situations much better, in dojo as well as in general life. I think this is the teaching of kendo, and the road towards that ultimate goal and what one learns therefore is the way of the sword.