Inventions usually start out with a small idea. Just like the story for honey bunches of oats, his daughter smiled because she knew he was up to something (and they never ever knew they would become very famous with their cereal).
Since many people are dying from diseases, you could make an invention that rates how close you are to get that disease. It could warn you on when you might get it (for example, it tells you that a person behind you has a flu, so make sure to stay away from that person.).
It would be called 'The-World-Is-Healthy' because it would decrease the spread of disease.
That would change the world.
