The stranger sitting across from you in the train drones on about their problems.
You listen and nod politely, although you are dying to put in your earbuds and doze off to soft music.
Or, at a company meeting, silence greets the question of who will take the minutes.
So you volunteer. Perhaps you are a person who is always willing to fulfill a request, or help out in a pinch even without being asked.
Who is especially nice, considerate, attentive, self-sacrificing — always there for others. Perhaps this is how people describe you. A very positive assessment, one might think.