Here´s my favorite inspiration sources:
I know some people get inspired by listening to a song or looking at a movie/tv series, I myself like having such things in the background when painting, my personal preferences are Vikings, Game of Thrones & ofc the Lord of the Rings movies. If you're more into the futuristic side of the hobby then I recommend Mad Max.
How it feels like when you look at all the stuff that need painting, a journey without an end....
Running A Blog or Project Log
Running your own blog or a project log on a forum has also helped me in the past. You start to feel a sense of duty that you really should get your miniatures painted so you can share them with the world. This method is usually great at first but it does get difficult to sustain, especially if you don’t get as many comments and hits as you would like. I have had project logs on Warseer fade away into the warp but they are great motivators to begin with at least. Hopefully this blog will continue to inspire me to paint, even though my painting mojo is rather weak atm (lots of stuff going on with the new house)
Please do share your inspiration sources!