Earlier today I made a post about why you cannot learn a martial art from home, and covering reasons such as needing the guidance of an experienced instructor, and also needing to practice with as many different people as possible.
As I contemplated this post I realized that I had completely missed out an extremely important part of the answer. You see, I had concentrated purely on the physical aspects, and completely missed out on the mental and philosophical side of martial arts training.
Martial arts are about physical training of course, but they are also very much about building up mental fortitude, perseverance, spirit, and a never-give-up attitude. You absolutely cannot get this from a video. It has to come from being constantly challenged to go beyond your perceived limits. A good instructor will always be stretching you beyond where you think you can go. Always just that little bit further, constantly stretching, constantly growing.
Over time you come to realize that you are much tougher than you ever thought you were. Not in a physical sense, but in the sense that you can face any challenge that comes your way, and you can get through it. These challenges may not always take place at training, but in your home, in your work and on the street. As tough as a situation might be, you will just know that you will find your way through, around, over or under it!
On top of the mental toughness aspect, many martial arts are imbued with philosophical teachings about how you can become a better all-round person. You will learn humility with strength. You will learn courtesy and respect. You will learn that you must always act with integrity. All these are not necessarily taught in lessons like you might have in school, but they are entrenched in the philosophies of the martial arts. And at training you are surrounded by these concepts all the time.
Hang around long enough, and they just become a part of who you are.