Someone thinks it is in luck / happens pleasant thing on him/her when another person(s) comes into what the someone was doing / about to do something, e.g. opening a door of an apartment building to enter it, due to the someone could do something good or not bad thing for another on doing for himself/herself. Most of the things can be thought like it to go good way.
But someone thinks it is not in luck / happens not pleasant thing on him/her due to he/she was not doing it for another but just for himself/herself.
Proper, defense and attack for legitimate self
-defense are essential or
must-to-do things, especially in physical fighting and definitely on the war.
Righteous, and victory for war.