There is always something to write about

Most of the time when you don't what to write about is when you're afraid it won't be perfect.

Develop the discipline to write even when you don't feel like it. If your aim is to make it your full time profession and to make money, there will be good days, and there will be shitty days, and on all of those days you'll have to write. 

So show up, get your butt in chair, and do it.

Journal first, if you have to warm up. Or (my favorite) write about something that bothers you at the moment. For ex...