'Butt in chair.' In other words, show up to write and treat it like a real job, not just a hobby. My mother used to repeat that quote that 90% of success is just showing up, and that’s very true when it comes to writing.
Making Shana a martial artist was pretty self-serving… she needed a pastime, and I already had some knowledge of karate due to my own experience. I do think drawing on that helps to build emotion and tension, simply because the sensation of sparring with someone is familiar to me.