This is so true. I'm stubborn also! Turning the other cheek is indeed difficult to achieve. But it doesn't mean 'not fighting' if there is no other choice.
Bruce Lee called it the "the art of fighting without fighting." I don't think even he was able to achieve such a state but I think it was a state he aspired to. Imo, It would take a very high level of Being to achieve such a state of 'turning the other cheek'. That is, it's 'Being Able' to act fom a very high level of control and mastery of oneself so as to minimize violence and acting with a maximum of external consideration along with a minimum of internal consideration.
But it does not mean being passive when the situation calls for being active and being active when the situation calls for being passive. It's having the 'Ableness' to make the proper choices in any given situation without being controlled by emotions and instant reactions. It's a tall order for anyone for sure! But it's an ideal to work towards. It's all about internal mastery, inner calm and not acting from fear
Example:
Note how the guy in the white hair (probably a martial arts master) acted to minimize confrontation based on a choice and not from egotistical emotional reactions but he would be more then ready and able to fight if he was attacked. Before, during and after the potential deadly situation his mind was calm enough to play a game of chess. As I said that's a tall order for anyone for sure. But in my mind that would be turning the other cheek because he has the 'Ableness' to do so.
I remember Theodore Illion saying in the book 'Darkness Over Tibet' :
"Real understanding in spiritual matters is the result of much bitter fighting, of suffering, spiritual agony and soul passion. Life itself would have no meaning if there was no fighting on all planes, if all was smooth and monotonous. Everything fights in nature. Every plant fights to get more sunshine, every animal fights for food; the angels themselves fight. Constant struggle on all planes to which it has access is the birthright of the creature. Woe to him who wants to put himself on a level with the Creator and escape fighting!”