This is the one most important advice I've ever received, and the one which every writer gives.
I'd been off from writing for over 2 months due to some studying I had to do (still have to, but I've rearranged my priorities), but the urge to continue working on my book proved too strong and, about a week ago, I took up my novel again. I stared at my chapter summaries: the one I had to work on was a brand spankin' new one, and I had no idea how to start.
But I didn't panic. No, what I did instead was go to my (wannabe) extensive library, picked up one of the many books I have yet to read, and started reading. Two chapters in, I knew how to start my own chapter, and I was off.
I've been working on my book pretty diligently since then, and whenever I feel myself getting mentally bogged down, I pick up the book, and continue reading.
Of course, I do believe that the style of book you read has an effect on you on the way it inspires you. For instance, I'm currently reading Joe Abercrombie's The First Law Trilogy, which is witty and bloody, has strong voices and creates a very (make that extremely believable) fantastical world (though it does leave one with the need to hiss and suck his/her own teeth/gums). This, in turn, has led me to find a new way to express one of my villains, for which I'm grateful (though I have to make sure I don't let my main character, 14-year old Olivia start thinking and acting like a torturer).
What about you, what book(s) inspire you?