In this case, the solution required no elaborate punishment, public insult, or dramatic confrontation. It required only a calm explanation and the involvement of a flight attendant when the passenger refused to cooperate.
That was enough to restore the proper boundary.
The Difference Between Standing Up for Yourself and Starting a Fight
One of the most useful lessons from the incident was that standing up for yourself does not require raising your voice.
People sometimes confuse assertiveness with aggression. They assume that defending a boundary means becoming louder, sharper, or more intimidating than the person who crossed it.
But those are not the same thing.
Assertiveness means expressing a reasonable need clearly and consistently. Aggression attempts to dominate another person. Passive behavior, meanwhile, may involve accepting repeated discomfort because challenging it feels too difficult.
The most effective response often lies between those extremes.
When the man placed his foot on my armrest, I first made a polite request. When he refused, I repeated the request and explained the problem. When he continued disregarding the boundary, I involved a flight attendant.