For my part, I'm very ADHD-brained and get extremely easily distracted by basically anything that moves or makes noise, so getting into The Zone can be difficult for me. Once I'm in it, I can easily bang out a ton of writing in a short amount of time, but getting there is the hard part. I've found that setting aside a distinct block of distraction-free time for writing can be really helpful. Turn off the TV, throw my phone across the room, close Discord and Twitter, even set my laptop on airplane mode if I really have to. Then just sit down for an hour and just write.
Music is also a really important part of my creative process. All media is, really — when I'm writing a specific kind of genre fiction I like to try and read or watch something in that vein before I start writing. Or it ends up being the opposite, where I read or watch something in that genre and then get the overwhelming urge to write something in it, lol. Either way, I try to consume the kind of stuff I wanna write. Music, I try to find a song that matches the mood of what I'm writing and then play that on loop about a bajillion times until the words lose meaning and its just white noise I can write to without having to think about it.
Overall I think I'm more on the side of discipline than emotion — I have a calendar that keeps track of how many words a day I do, the status of my various projects, etc. I think ultimately writing is, to me, more of a sport than an art. There's definitely elements of artistry to it, but at the same time you need to constantly be exercising and developing your writing muscles lest they atrophy. There's a quote I quite like on the matter, by Chuck Close:
“Inspiration is for amateurs. The rest of us just show up and get to work. If you wait around for the clouds to part and a bolt of lightening to strike you in the brain, you are not going to make an awful lot of work. All the best ideas come out of the process; they come out of the work itself.”
Obviously this is hardly true for everyone, but I like the feelings it inspires.