"If you wait for inspiration to write you’re not a writer, you’re a waiter." Dan Poynter.
For those who have to wait for their 'muse' to speak to them or have to be in the middle of a forest or hanging upside down from a cliff before they can start writing, this is a great wake up call. Sure, it’s nice to be hit with a sudden bolt of inspiration and know exactly what you want to write and exactly how you want to write it, but it’s also extremely rare. Personally, I find that the moment when inspiration is most likely to strike me is when I’m already writing. Be a writer, not a waiter (I don’t mean someone who serves tables. Absolutely be that kind of waiter if you want to).