The line: "Writing is the hardest thing you will ever choose to do."
Yes, I know I'm going to sound insensitive here to a lot of people; but seriously, if you believe that or even consider believing it, and if you are an aspiring or working storyteller, novelist, poet or anything else in that area, then maybe you're in the wrong metier. Go and do something else and save the world from your ruminations.
I'm saying this because I actually am a storyteller, as evidenced by the dozen+ novels and another dozen+ feature-length screenplays I've written, rewritten, sweated over, and even (in the case of one screenplay) made into a movie. The only thing I can think of that makes writing 'hard' is that it takes a lot of time away from other important things, like your family and friends, and that it can put you into situations where those around you wonder if you're slightly insane maybe, because you're never quite really where you should be in your head, but somewhere off in story-devising lala-land.
Writing takes more time away from such things than most activities in the 'art' domain*—all of which I consider 'optional', because ultimately their main aim is to make yourself happy and content and fulfilled and blahblahblah.
Depending on what you write, it may not take that much more time away.
For example, first drafts of screenplays have rarely taken me more than 40 hours to write; and these often are pretty close to the final product, since that's my methodology: I never write anything down that I haven't bounced around in my head for quite some time before sitting down and keyboarding it in.
Novels are a different proposition, because they have many more words; but when I'm on a roll, I can churn out 4k+ words per day no sweat. The main issue is my typing speed—I still can't touch-type after several million words written with typewriter or keyboard!—and the fact that I also have what's commonly known as a 'life'; i.e. family, obligations, day-jobs, etc.
If that sounds like I'm bragging, it gives the wrong impression. I'm just wanting to point out that this thing about writing being the hardest thing you'll ever choose to do is at the very least not absolute—and it shouldn't be stated that way. And anybody who states it as it it were some truth either hasn't got a clue what s/he's talking about or wants to sell you something.
Anybody for whom writing is the hardest thing to choose to do probably does not have a burning need to tell stories; because if you do have that need, writing may be difficult at times for all kinds of extraneous contingent reasons, but that's got nothing to do with writing per se. Instead, it's possibly because you don't have any story to tell that you believe in. Or maybe because you really, really want to be a writer, but you don't understand that that isn't enough. Because you don't understand that it's not about 'writing'—which is a mechanical thing that requires both skill and artistry, but these can be learned; the former more so, while the latter arguably requires a certain something in order to provide the fertile ground for the learning to take hold. It's about the need to communicate emotions and ideas through the medium of prose-fiction (or poetry, if you's so inclined; which I'm not) or maybe the 'play' or 'screenplay' format.
I know many writers, like a lot of other artists, like to cultivate the mystique of their self-fulfilling passions for the rest of the world. Like they were something special that lifts them above the common ruck.
I do understand what it means to live a life where you're the only one who actually understand what drives you to do what you do. I've lived with it for more decades than many of you have been alive. But, let's be honest, doesn't that apply to everyone, really? No matter who you are, do you really think you're not, at least in some part of your psyche, an island, separated by an uncrossable ocean from everybody else; even those closest to you?
No, writing per se need not be 'hard' at all; even though the world might make actually finding time for it a quite difficult. But that's all.
Seriously: think about it for a moment and get a sense of perspective and douse your desire to indulge in self-flattery or whatever form of monomania might have a grip on you. There are literally billions of people in this world, who have much harder choices to make than you with your desire to be a writer; and the consequences of whose choices will have a far greater and profound impact on themselves, those close to them, and possibly the world as a whole.
* I'm also a photographer, and that also takes up a lot of time, but it is far less anti-social an activity.