You may have already read 'The War of Art' by Steven Pressfield. It's a classic, about the everyday struggle to be creative and productive. I highly recommend it, even if you don't think of yourself as particularly creative.
As Seth Godin pointed out on his blog this morning, Pressfield's new book is available as an eBook for free at the moment, with no need to sign up to anything. It's focused on writing but I'm sure will have other applications too. You can grab it here: