"Children, let us love not in word or speech, but indeed and truth."
Even the first and second generation Christians that St. John is addressing must've felt the temptation to talk the talk without walking the walk. But the apostles saw Jesus put the two together again and again. Even as bishops and leaders they would not have been able to separate the beautiful first Mass of Holy Thursday from the call to service within Holy Thursday.
[This one kinda has to be listened to since it involves listening to clips from a Broadway musical.]