Wanna be a professional writer? Act like a professional. So many people say that they want to be writers but they don't want to spend time writing. Unless you can afford to employ the services of a ghost writer to do your writing work, you'll probably need to really work.
Carve out time for your writing and treat it like a job. Create working hours and go to a desk (or kitchen counter or whatever you have) and sit there. Stay at your desk until the job is done. Set daily targets, much like you do/did at work. Remember things like overtime? Work overtime. Try not to leave your desk until the job is done. It's a job and you want to get paid so you need to have a good work ethics.