Whatever the mind of man can conceive and believe, it can achieve. ~Napoleon Hill
If you have a desire to accomplish anything, you have to genuinely believe it is achievable. You have to be able to imagine it. If you can envision yourself doing whatever it is, that is, making it so realistic in your mind's eye that it feels as though you have already accomplished it, you are halfway there.
On the other hand, if you imagine yourself longing for whatever it is you dream about doing, and you picture one stumbling block after another, you have already lost.
What Napoleon Hill was teaching us was this: If you have an idea, say an invention for example, and you believe that it is not only possible to achieve, but you are the one to make it happen, you CAN do it. You might have to do some research. You might have to experiment a bit. You might even have to backtrack and rethink some elements of the project, but, if you persist and continue to believe it is attainable, you will succeed.
Henry Ford's V8 engine was one such project. His engineers said that it couldn't be done. Henry said it could. He told them to keep trying. A couple years later, they finally had a working model and went into production.
Visualization Is A Powerful Tool
Every great invention began with a single idea. A visionary sees a need. That same individual creates a rough sketch to share the concept with another individual. The design then is used to create a working model. That's how things get made. It worked with Philo Farnsworth (He invented the television).
It all starts with a single idea.
Indeed, if you can picture it in your mind, and believe that it can be done, you just might be the one to do it.