Philo: Harm and Offense

"Harm is a one-way street, while offense runs both ways. You can be harmed against your will, but never offended against your will. That is a powerful distinction. And I urge you to consider the benefits of drawing it as often as necessary. You can maximise your ease by refusing to take offense, or maximise your dis-ease by seeking it at every possible turn.

You cannot be offended without your own consent."

But if the reaction is instantaneous and spontaneous, you're offended even if you decide rationally and calmly not to take offense. You just decide not to let it affect you, but you have been offended and that's unchangeable. right?

Philo confuses me.