There are so many theories about inspiarion but in my particular case I'm lucky enough to find inspiration wherever I go.
The key is to pay attention. I could be inspired by a beautiful contryside scene or just by a patch of rust in the subway. I found that taking photos (I just erase them afterwards) is a way of focusing on the present and really helps to see contrasts, lights and shadows etc.
I tend to work from emotions more than from memory and it's important for me to work every day even just for a few minutes, to be in contact with materials, to transfer the emotions of the day into my work.
And I never forget: "Inspiration exists but it has to find you working." (Picasso).