Writers have different methods of tackling their craft. I'm going to take a few minutes to talk about three that I have used throughout my writing life.
The first method is to wait for INSPIRATION. This essentially means doing anything but writing while one waits for their body to be possessed by a muse who gifts them with an idea from the great beyond and moves their pen for them. The writer is but a vessel for the divine spark. I tried this method out, as so many do, early in my writing career. Sure, it's a little embarrassing, but we all do silly things when we are young. No really, this is an awesome method for writing...nothing. I exaggerate; I did actually write while waiting for inspiration. The young are easily inspired. I wrote dozens of poems, some weren't terrible, most were maudlin at best. I wrote my first book using INSPIRATION. An idea implanted itself inside of me and I wrote diligently until I got it out. It was a terrible book. The point is that at best waiting for INSPIRATION produces sporadic results, and usually poor results.
For a while, I used a time goal. Here you set an amount of time, an hour, four, eight hours, whatever is reasonable for your schedule. For that time you sit in front of the keyboard and voila, you are writing. Only you aren't always writing, and since there is no word goal, there is no real obligation to write anything.
The method that does work for me is using a word count goal. I keep a modest goal of 500 words a day. With that goal in mind, when I sit down to write I just write. Editing, research, writing this blog, doing all the many things an indie author has to do; none of those count to satisfying the word count. Most days I write more than 500 words, every so often I miss my goal. But I track my word count daily. I have a little blank book that I use, the cover is the Abbey Road album. It only takes a moment and it serves as a great motivator to write. At the end of the month I can add it all up and see how I did. For instance in December I missed my goal 8 days (I blame the holidays for some of the missed days, but not all of them) and made it 23 days. My average was 539 words a day for a grand total of 16,720 words for December. At that pace it will take just about 5 months to finish a draft on an 85,000 word book.
Find the method that works best for you. If you aren't writing, whatever you are doing isn't working and it is time to try something else.