The difference between a great idea and a great business is that someone actioned the great idea to create the great business. And don’t be fooled by the “started in a garage” hype either, most great businesses arrived where they are after many great failures. You just don’t get to hear about those.
So now we have that straight what about that idea of yours? In the words of one famous brand, just do it. Take the idea, start writing about it, take notes, turn it upside down, make silly suggestions, draw cartoons about your idea, match it to colours, give it a voice, talk about it into a voice recorder, present it to yourself on video or Powerpoint. Whatever you do don’t let it go!
During this process every time you find a reason it won’t work bend it, shape it, mould it into something that will work and when you hit the next dead end re-shape it again. You don’t have to spend a penny, you just have to keep thinking about it, adding to it, improving it both in your mind and on paper. At some point you will not be able to manipulate it any more, you’ll hit a wall. Forget about it, leave it alone.
After a few days, maybe a week or so see if your idea still stacks up. If it does, then get into gear and action it. If not move on and have another Great Idea!