I think that inspiration doesn't exsist. I prefer the Stravinskij's way: he thinks that composing music is a regular exercise to do every day. Pheraps, you go through a particular period: you think it's an inspired period; exploit this moment, but I think that a great piece (with a great orchestration, a good timbric fusion) is the result of an hard work. Listening, Learning, Reading and finally Writing Music: it's my approach.