The problem with being a writer is that most of it happens in your head while you're sitting in a room by yourself. Most of the writers I've met have been introverts, who live mostly in their heads anyway, so it's not a sacrifice--but it can become sort of a default. And stories need to be fed to turn into books.
So go looking for Story. Watch informative tv--or shows that are really good in the writing and execution areas--so you can find new things to think about. Read books not like what you're writing. Read magazines. Read blogs. Go to markets and cultural events. Turn down other roads you don't usually take and see what's down them. Go on vacations once in a while.
And pay attention to what you see and hear and what it makes you think about--because that thinking-about is the first seed of an idea. Take notes. Write observations and interesting facts down. Save images.
I firmly believe that ideas happen from stuffing your head with as much random info as possible, and letting your subconscious play around with the puzzle pieces until it sends a new thing upstairs to your conscious. And I firmly believe that all information is useful for a writer. So save it. Curate it. Mull it over. Keep it for later.
And get in the habit of going looking for neat scraps to keep! Feed that story-well!