Many of us undertake the study of a marital art with a preconceived notion in our heads. Some are looking for discipline others are looking for confidence, still others are seeking a form of defending themselves. I want to suggest that while you may go in with any or all of these ideas into the study of a martial art, you may be surprised to find that they are all what would be considered secondary effects to the training that is martial arts.
When you diligently study and train, it requires discipline, like any endeavor that takes time to achieve or accomplish. And so discipline is cultivated, honed and forged into the character of the student. Likewise with confidence, executing techniques in front of a mirror, be it basics or kata requires little confidence. Change the setting from a mirror to a dojo or to a training hall filled with students and the context can directly influence your performance. "Are they looking at me?" The most obvious answer is - yes. If you are a senior, you are being observed so that the juniors may emulate you. If you are a beginner, you are being observed so that you may be corrected. (This is not to say that seniors don't need correction, sometimes they need more than the beginners.) The point I'm trying to get across is that if you dislike scrutiny and criticism, practicing a martial art may be something for you to reconsider.
In regards to defending yourself, I hold fast to the position that martial arts are not self defense.
That being said, with enough years of training, certain actions and techniques can become reflexive and lead to a furthering of study as to what may be used for self-defense. Learning the applications of katas (bunkai) can lead to a discovering of techniques that can be used to defend yourself. In many cases though, this is usually a journey undertaken alone or after many years.
So why study a martial art? If I'm not going to get what motivated me to join the art initially why should I study a particular art. Honestly I can say that one of the greatest attributes of martial arts (and I'm not making distinctions here) is that while training you get to discover yourself. No, I don't mean a trip to nirvana or enlightenment, although I'm certain those are also attainable through martial arts as well as other disciplines. What I'm referring to is that in the process of training you will discover and uncover your character, your strengths and your weaknesses.
What you do when you do discover these aspects of yourself is an indicator of your commitment. Do we downplay the weakness and emphasize the strengths? Or do we take a good look at those areas in our training and life where we need to train a little harder, be a little more diligent, have integrity and fulfill our word - first to ourselves and then to others. That is one of the encounters martial arts can provide you, if you are willing to embark on the path.
strong spirit-strong mind-strong body