I say fighting back is the *only* response to bullying. Period. However, I'd qualify that by saying that "fightback" response by no means necessarily has to be physical. There are many ways to fight back but at the end of the day - in order for the bullying to cease, the bully must know that he or she will be met with resistance [and possibly physical force] should they wish to continue the bullying.
This applies to equally to the workplace and the schoolyard. I have witnessed both. Regarding children, generally we'd advise them to report bullying in the first instance to a teacher. Bullying is treated with extreme gravity here in the UK as I'm sure it is elsewhere. The school will deal as severely with the bully as it's disciplinary framework allows [which isn't always a great deal imHo] however where the school is impotent and utterly powerless is afterwards out on the street. This can be the most terrifying time for kids as reporting the behaviour will often have led to an escalation in the scale of the problem and is also why many cases go unreported - the child eventually reaching that point where they feel so failed by so-called right-thinking adults that they really do see no other release to the relentless daily torture of bullying than suicide.
As martial artists, almost all of us will train concepts such as situational awareness, de-escalation and conflict avoidance but bullying is one of those advanced cases where we as martial artists would be taking the split-second decision to fight or run. The problem with bullying is that it's recurring and serial in nature meaning that were you to have chosen to run previously, not only will the bully have sought you out again but now your fate is sealed, the bully knows you have no confidence to fight back.
I maintain therefore that the only practical mentoring we should be showing our young people in particular regarding bullying is to fight back. Physical or non-physical will depend on the situation but for bullying to cease, a line in the sand must be drawn with confidence - and it's confidence we can give to our kids through our martial arts.
It would be my wish that we would hear the inanity in our own attitudes and stop blindly taking the offender's side so often. Consider the victims.
Respects!