Many people think that in order to become a prolific writer you have to write full time. I thought this myself until I started meeting lots of successful writers who had full time jobs. Back then I wondered how they did it; be so involved in work and then to come back home and start writing.
But then I realised these writers had traits in common. They follow a strict routine. They probably write everyday. They write regularly so they always have a constant flow of ideas floating around their head.
They probably write after using an outline to map out ideas. (Before you pantsers send me hatemail to object to this, I'm going to insert a clause here to say I know this isn't always the case but I am an outline writer so I'll stick to what I know). Writers who outline say once they've finished they just have to fill in the blanks in their first draft. They write their first draft to get the story down on paper. Then they go back to edit and rewrite it while ignoring the voice of self doubt that tells them their writing is rubbish. Through ignoring this voice they continue to put pen to paper, thus improving their confidence. They just sit down and write, producing one book after another.
If you really, really want to write you'll always find a way. I know one writer who took ten years to finish his first novel. Now it's available in a major U.K. bookstore. People who make excuses why they don't write all have one thing in common: their heart really isn't in it. They use the excuse of being too busy with other things in their life so that's why they fail to write. Sometimes I think you can write better with a little bit of outside pressure. There's just enough stress to get you focused. I know I can write more efficiently when I have a looming deadline in front of me.
Are you a prolific writer?