I used to write regularly in high school. These were the days before the internet, of course, so there were fewer distractions for a teenager and all I did was read and write. After finishing one story, I quickly moved on to another. I found inspiration all the time, and was disciplined enough to see almost all the stories through.
That's a bit harder to return to. The first book is barely out, but I've been training myself to think of "the next one" already. There have been a few false starts, but giving up shouldn't be an option.
Inspiration, I'm reminding myself, is more of a mode. I just have to get back in that mode, because surely it'll get easier once it's back in my regular routine. A friend just told me an anecdote about her life that is now swirling in my head, hopefully I get to create something out of it. She's even looking forward to it. :)