Isaac Asimov woke up every single morning at dawn and he would type until noon.
Isaac Asimov published 400 books in his lifetime. How did he do it? Every morning he woke up at dawn and he typed until noon. Not because he was a genius. Not because he could write better than you. Why then? Because he did what professionals do. Every day, he woke up, he sat down at his work space and he wrote. What we understand about professionals is that they’re doing their work. They do it every day. They do it because that’s who they are, it’s what they do. It’s not complicated.
Someone who digs ditches doesn’t “get around” to digging ditches in their spare time. They put on their overalls, they put on their work gloves, they get a shovel and they dig and when the shift is over, they’re done digging. They don't have a whole discussion with themselves about whether they’re good at digging or whether they feel like digging or whether they’re in the mood to dig. They just dig.
Most of us don't have to dig. We get to make art. So, if you want to write, set a time, set a limit, and write. It doesn't have to be good writing. You just have to write. So, get to it! Make your art (or your sales pitches or your code or your proposals or your designs).
Related: Economic Sense Doesn’t Always Make Logical Sense
 paraphrased from Godin, Seth. “Leap First”