I find writing to be very easy to get down onto a page, it's the editing and making it good that's difficult. Like, I spend way too much darned time on editing. I wish I could feel content with only editing a chapter once and throwing it up, but I think I'm insane shrugs. I don't know, I feel like writing is also a constant struggle of just pure will. I mean, most of us don't have very big audiences, and so you pretty much have to be writing the story for your own pleasure due to your own determination.
I think it also depends on the length of the story. I said it before and I'll say it again; short stories are wonderful because they don't take up too much of your time or energy and you generally don't care as much if no one reads it or if it's any good. It's also easier to keep the story clean and tightly knit when it's shorter.
When things are long-form, it's far worse. I still love writing those types of stories, but man, long-form is truly a test of your will and determination as an author, haha. It is so hard to keep things consistent, entertaining, clean, and tightly knit. Especially when you have to start asking yourself things like, "Okay, do I really need this character or am I just adding characters to the story because I'm getting bored with it?" XD.
So, I dunno. It's easy and it's not easy I guess.