I wasn't planning on doing this today, but I had a pretty bad day. I came home from Uni after lectures and needed to do something to occupy my mind. Before I knew it, I had measured out grain and started heating up water.
As with most of my brews, I get an initial idea from somewhere, can be a conversation, can be something I've read. That will make me want to brew a particular style of beer. This is then matched to what ingredients I've got, and what makes it interesting to me.