Hello there,
I am a fairly analytical person so I get my drive from realising the end goal of the website. Without knowing that, I can't design a plan to get to that end goal and am thus....highly unmotivated.
I presume this is just human nature however, although some creative people seem to be driven by other things than the end goal. While this can produce great stuff, it's an unfortunate attribute to posses when operating in the business world.
What also helps immensely for me is there is personal gain to be had from the end result. This is I guess...why capitalism works (well...lol if consider capitalism a working system).
As for inspiration. When ever I am at a good website or I see good copy, I bookmark it. I then have a massive list of stuff to browse through when I need ideas. Although I seem to always have too many of those anyway :|