Inspiration can be found all around you and can come at the most inopportune times, such as when you don't have pencil and paper or a camera ready to record the event.
The tune of a song, a picture or quote in a book, or even a random encounter with another person may trigger a reaction in your mind that ties two or more loose ends together. This new connection could be the missing link that enables you to turn your idea into something much larger.
Getting from the spark to an actual product is the real challenge. The mistake that I see people make is to take the source of inspiration and then directly translate that into their project. More often than not, it is not a clean fit and does not come across as fully integrated into their new design. Experienced designers and architects can successfully transform a fleeting thought into a workable idea. This is what you should be striving to achieve and getting to this point is less than clear.
The place where you leave the source of inspiration behind and push forward in a direction to create something new is called the point of departure.
If the spark generated momentum for your idea, then the point of departure is the place where you commit to your new trajectory and make something happen. The spark may continue to serve as a source of power for your project, but it shouldn't drive your decisions.
Pushing off from shore in a small boat with only an idea and a loose plan in your head can be a daunting task, but this kind of effort is what is required to truly create something new. Breaking off in a new direction, especially if counter to public opinion or current trends, is not easy. However, you can get there faster when you can identify your source of inspiration, that thing that gave you momentum, and then break from it so that you can work to make something of your own.
It does sound counter-intuitive, but there will come a point where that spark may hold you back and you need to be willing to part with it. The point of departure is important to understand because it is the moment that people start taking an idea seriously and work to bring it into reality.