"There are only three Muses: one who is born from the movement of water, another who makes sound by striking the air, and a third, who is embodied only in the human voice."
Muses are the origin for such words like amuse, museum and music... and these are the places you should go to find the Muses... what you find amusing, collections of interesting things and things that touch you, make you feel, wake emotions in you...
In Star Trek Deep Space 9 there was a "muse" who inspired people to greatness while nourishing themselves with their life.
Would you change the rest of your life to the chance of creating a masterwork?
You don't need to...
Where do your ideas come from?
Poet's Journal, Part II
Where do your writing ideas come from?
Stephen King's answer (not the warehouse one ;-))
The Idea Store
Where do ideas come from?
Philip Pullman's answer (P.S. Philip, perhaps that was a joke as well...?)
Simon Rose: Where do ideas come from? Part I, II, III and IV