As a hooper, we hear this term, be a professional.
This means take care of your body, put in the extra work, watch film, train, have passion for the game and the game will love you back. Understand your role. Be coachable. Etc.
Not everyone has this. I know we want to believe they do but not everyone has the right ethos. Sometimes, you can take someone with bad ethos and they can hit massively like JJ did but most of the time, bad ethos will result to bad performances.
Teams that didn't know Ant Edwards well thought he had terrible ethos but those who met him realized, he wanted it and had the right internal qualities.