This is an interesting thread, pretty good advice in places to.
Passion for something is a very 21st. century notion, a word that is bandied about, but hard to pin down. I would say that Determination to never, ever, ever, give up is as useful to the aspiring fATPL, demonstrated by some of the posters on here. Certainly learnt by myself 27 years ago when I passed my IR in the middle of the Air Europe bankruptcy. 2.5 years of trying to get a job, finally materialized into one, and the wait was extremely trying, but worth all the effort in the end.
There are differences between then and now. The 90's was the tail end of the good times to be a pilot. I was lucky enough to end up with a legacy carrier which had great t&c, but post 9/11 everything has been a battle to keep them. With the failure of Thomas Cook a few weeks back, I now am looking for work again in an environment that I barely recognise and for pay that I would have laughed at a month ago. If you are new to this game (which I am insofar as selection processes go) I would greatly recommend a course of interview preparation. BALPA has thankfully organised these for the TC pilots FOC, but having done it, I can genuinely say it has increased my chances of surviving a selection day by 100%. The dead hand of HR looks at you from angles that you don't see yourself and you are judged by the smallest infraction of a set of criteria that only they know. But the criteria are generally similar for each airline, so know the game to increase your chances of winning it.
Thankfully, I came to aviation late as a 2nd career, so I'm at an age to walk away and hang up my headset. I loved the first 10 years, but the next 15 made me think that I would not recommend the life to my children unless they just had to do it, back to the passion, I suppose. The money today is there eventually, but it is not so great that plenty of other jobs, which are easier to achieve and hold onto, can't equal. I don't regret travelling the world and having some amazing experiences to remember doing long haul, but to sell my soul to do 4 east Med trips a week, no thanks.