The question was, 'What marks a true professional?'. While there is a degree of self-consciousness and embarrassment for many of you in answering such a question, which has resulted in the kind of humorous replies seen above, it's a reasonable question and it deserves a sensible answer.
The first thing to say is that it has nothing to do with landing lights! Procedures in a particular aircraft and a particular environment may be evidence of a professional attitude, but they do not define anything.
Professionalism comes from many things, but it is founded primarily on integrity. Integrity drives you to do the things you know are right even when it is difficult, time-consuming, embarrassing, or requires more effort than not doing so. There are many situations in everyday life, as I'm sure you are aware, when these things apply. How often have you failed to do something you know to be right because you couldn't be bothered, or it would have taken extra time out of your day, or it would have involved an element of exposure to ridicule or even threat? You know, deep down, that there is probably at least one situation every day where you've taken the easy way rather than the right way! We all do it, in many, many different situations.
Well, once you are involved with aircraft, that has to change. Whatever you do in your life outside flying, once your working day starts integrity drives everything. Doing the right thing becomes infinitely more important than doing the easy thing, because your life, and several hundred passengers' lives, depends on it. At your end of the career, it starts with learning what the right thing is in the first place. That means equipping yourself with the knowledge required to inform your choices and actions. That doesn't mean knowing everything, incidentally! A professional knows to avoid cramming his or her brain with information irrelevant to the primary task, because they know where to find that information when it is needed. You'll find that a very great deal of the information you need is quite adequately stored in manuals and textbooks rather than in your brain, taking up space needed by more important stuff.
Developing a professional attitude means listening to and studying the methods and actions of your mentors, be they groundschool instructors, flying instructors, training captains, examiners or line captains. Not with a view to criticising them (you're not yet in any position to do that), but to see what works, what works well, and what could be done better. With very few exceptions, even the worst of your line colleagues in any reputable airline will be making a reasonable stab at professionalism, and it's up to you to learn from each and every aviation professional you come across in order to improve your own effort.
That sounds a bit earnest and dry, and indeed you will find people who take it all so seriously that they do nothing other than what I've described above. However, like an elite athlete, a professional how to match the effort expended to the requirements of the task at hand. There is little point, for instance, using huge amounts of brainpower and energy worrying about all this stuff in the cruise if by the time you come to the landing phase, you're too knackered to do a decent job! The professional will know how to use the appropriate time to relax so that they are at the top of their game when they need to be. Again, knowledge - of the aircraft and the environment - is key to being able to make this judgement, and integrity is fundemantal in acquiring the knowledge.
Most of this stuff is there, inside you, whether you know it or not. The various formal and informal selection procedures you will undergo over the next few years are designed, in part, to determine that only those with an adequate level of integrity will get through (though, before anyone tells me about Bloggs of SuperAir, any selection procedure is imperfect!). As long as you do what you're told, when you're told to, and you spend some time thinking about why you were told it, you will acquire the knowledge you need at about the right rate so that, when the time comes for you to command an airliner, you should have all the qualities and knowledge required.
Work hard, listen to those who've been there before you, read things like Chirp and Pprune Tech Log forum and Safety and Q&A forum, and don't forget to enjoy yourself. It will all come together in time!
Scroggs