Inspiration for creation

What kind of inspiration do we need to start a new creation?  I've tried beautiful, peaceful locations but tend to find the views a bit distracting.  I've tried a darkened room with minimal external stimulus but the ideas don't flow to order.  It seems that inspiration will still strike at the most inconvenient moments - in crowded public transport.  I was on a tram in Lisbon recently.  Not one of the picturesque, rackety, pre-WW1 trams that wind through the impossibly steep and narrow streets of the Alfama (see above), but a new Siemens, double-length tram full of sweaty commuters on a busy stretch of road in the commercial centre.  I was jammed against the door on one side, a waist high glass partition on  the other, close enough to my fellow passengers to surmise a great deal about what their personal hygiene routine was like and what they enjoyed for breakfast. I had a sudden idea for a story.  Being a conscientious student of creative writing, I now carry a notebook almost everywhere I go.  Unfortunately on this occasion I could not move my arms, let alone reach for a pen.  So, while the tram stuttered along between traffic lights and inexplicable hold-ups, I tried to hold that thought.  Fifteen minutes later, finally emerging from the tram outside the Monasterio de los Jeronimos at Belem, I joined the queue to see inside the wonderful 16th century church and, by the time I wandered back outside, blinking in the sun, my story had dissolved away to nothing and the strongest idea in my mind was how to get back into the city without having to travel on the number 15 tram.