I had practice in judo, karate and a bit of MMA as a schoolboy. I had fights on streets few times, but it doesn't relate to bullying. It was arguments between us, children who had lots of energy and wish to fight. I never been bullied in my life. But. When I hear a story of bulling or see as someone is bullied my heart is breaking. It's unfair and disrespectful when someone with knowledge and experience of fighting trying to mess with someone who simply wants to live in peace.
When I was 23 I have been living and serving in army for a year. In Russia we have compulsory service. If you are healthy man 18-27 y.o. and not a student (anymore or yet), you have to go to army. So in one unit of army we had people of all sorts. One more thing I want to note, we have very severe and unpredictable (and stupid) law system in Russian army. Some bullies can mess fights often and to be free, and someone else can fight back, broke a bully's nose (or something) and to be jailed for 1-2 years.
My height is 6'2. I visit gym regularly since highschool. I respect people around me. No one tried to mess with me even in army. By the end of my serving we had a trip from one city to another. There were 20 soldier, most of them were new to me, but they already knew each other well. I was away from my mates with whom I served before and get along well. So it was new people to me. There were 4 guys from criminal regions of Russia among us. They were like a gang. They tried to bully almost everyone. One of them was born rich. He traveled along Russia and Europe cities in order to have street fights against other football fans before army. He knew if he breaks a law, his parents can buy him freedom. The rest 3 wasn't rich, but they didn't mind to break rules and laws as well. Most of people tried to ignore them and bullying or just tried to walk away. But they didn't stop. I was a witness and I was able to do nothing (due to laws I couldn't fight them, due to army tradition I couldn't report about them). It was hard to watch. Especially, how they bullied one guy. He was 18 y.o.. Extremely shy person. He almost never spoke and if he did, he did it very quite. I looked at him. I felt like he is mentally broken already, I felt like if I keep just waiting and do nothing he can kill himself, and it looked real.
Next time they tried to bully him I started protecting him. It seemed that conflict was solved by words. But we all were living and serving together. In few days after this they started trash talking me and tried to provoke a fight. Well, it happened. I slammed one of them to the ground. Another one kicked me in the back. I threw him down too. I was focused do not damage them (do not strike), but it was a real fight, anything could happen. One guy, who I stopped from fighting them before was the first person who rushed in the fight and started to calm us down, started to try to stop the fight. Then other guys rushed in between us and lucky to everyone this fight was stopped. If it wouldn't, it could be only loss situation to me (break a law and be jailed or be beaten). Thanks god no one had injuries after all.
Next day our authority decided to divide us all and to send us to different places to continue serving there. I'm happy everything ended like that. I don't know how exactly serving of guys that were bullied went on, but since that gang was divided it's definitely became better (as a single persons those bullies were much more sane).
Now I'm 28. Two years ago I was witnessing a conflict between two woman (around my age) in Moscow tube. It was midnight. They were a bit drunk, but it doesn't matter. They almost had a fight, no other passengers gave a damn. I was standing close to them. I hugged them and said "not worthy to argue". After that one of them started crying (I dunno why) and another one started to comfort her. Odd ending, but either way better than fighting
We should not hesitated if we see someone is going to be bullied around us, or just in trouble. We should keep in mind that those people have families and they think and care about them, and waiting for them to be home and safe.