"People with the same disease share sympathy." - Japanese proverb Martial arts training is one of the most difficult things a person will ever do.
It is difficult because throughout the journey, the training tests and simultaneously forges us physically, mentally, emotionally and spiritually. Luckily, it usually doesn't happen all at once even though it sometimes feels that way.
This "suffering" is the first step towards our understanding of compassion. When we suffer we are better able to see the suffering of others and then we realize what they are talking about in Buddhism when they say, "Everyone suffers." We are suffering and then we learn that at the same time other people are going through their own stuff too. It doesn't matter if you are the teacher or if you are the student. Everyone is suffering to some degree.
Compassion is defined by Google as, "The sympathetic pity and concern for the sufferings or misfortunes of others. The Buddhist definition of compassion is "Wanting sentient beings to be free from suffering."
We are not alone in our suffering. Like all people, we are all good and doing the best that we can. Like all people we are all suffering and going through our own stuff. When we understand this then every person deserves kindness, compassion and forgiveness - just as we do.