I have visited many martial arts schools over the years and I am struck by the lengths some teachers go to provide a fun, enjoyable experience for their students. Pleasant, colorful atmosphere, crisp, starched uniforms with no blood or sweat stains, minimal contact and almost no danger of injury. One of my favorite new martial arts fads: padded weapons such as sticks, swords, long staffs, etc., that are nothing more than PVC pipes covered with foam...so nobody gets hurt. Believe me, you learn a great deal from getting your fingers mashed by a wooden sword (boken).
You will not learn anything about a fighting art unless you fight...constantly. This means applying the techniques of your given style as close to reality as possible against someone having a skill level equal to or higher than your own. It means frequently placing yourself in uncomfortable situations so that you learn how to deal with physical and mental stress in a calm and focused way.
Be it karate, aikido, mma, etc, a serious sensei or coach will create and maintain an atmosphere that poses real danger to you and you will experience pain, especially during the beginning stages of your training. Your body and most importantly your ego will suffer. That's what budo is about. It's not supposed to be a warm, fuzzy experience. If you are seeking enlightenment through martial arts, you simply cannot avoid pain and discomfort because that's where the real training is.
Things like comradery, respect, trust and friendship happen in places and experiences where people suffer together and are exposed to the same danger and discomfort. It's not supposed to be like going to a tennis club or the bowling alley.
It's supposed to hurt.