Martial arts is a process of contrasts. You are learning about violence to not be violent. You are learning about self to be selfless. You are working on yourself to help others.
No one can be truly successful at martial arts without the help of others. Your training will affect those you surround yourself with, without a doubt, in big or small fashion, depending on your depth of perception.
Very few things we do in life can have such a profound impact not only on one's self, but those around them.