Get your Gi on and get to the dojo.
A black belt is only the sum of hundreds of classes, not a special talent. Losing momentum is the cause of many failed hobbies, talents, dreams and projects. In trying to get any goal accomplished, one forgets that this is made of a thousand little steps. You don’t have to do amazing feats. You just have to go to class regular.
There are as many reasons to halt than there are students. Each has his own personal faith. It says, that within all of the martial arts only a very few actually get to the goal and become at least a 1st Dan black belt. Must be still something very special this black belt, as in compare to university courses most finish with 50% or even higher graduates.
In martial arts, after years of dedicated training, the enthusiasm begins to slow down. Sometimes, it just stops suddenly but for the instructor, no student slips away unnoticed. (Should!)
When the student starts showing up less or even stops abrupt to attend, there are many reasons why this happens. Money must be earned, family requires an investment of quality time, and for many teenagers, just getting to the dojo relies on parental availability and willingness. Mind you, in the old days we used to go by bus or cycle. Injuries can cause an unwanted break which becomes a longer abstinence. In my personal case once it was the new fiancée which stopped me going.
A missed class can easily become two. Two classes becomes a month. And so on.
But hey, keep on mind! You can always go back. The Sensei and any other students will be delighted to see you return. All that matters is that you make the decision to put your Gi on and get to the dojo. And just in case you thinking about the excuse, that you not fit enough anymore; so few people are genuinely fit when they start in the first place. Fitness will come back faster than you think, and honestly? It’s not that important.
My maxim is, never miss training. Only exception is your mother’s funeral. OK, this is a bit drastic, but we do traditional Japanese Jiu-Jitsu and there is little room for being weak.
If you have a virus, stay out the dojo. If you have an exam tomorrow, still show up, as it will do you good. In case of injury or light illness, always attend and sit and watch.