Ideas are a cornerstone for new businesses. They pop up in people's heads at the weirdest times. That is good.
Some are centered around the job that you are doing, or a hobby, or a comment at last nights social meeting.
Most get passed over as "Awe, that won't work". Or you tell a friend about them who tells you the same thing.
These questions and a bunch of others are frequent in the forums where I participate. Many people do not have a clue what they want to do, but, the idea of having a business of their own intriques them.
One suggestion is to look into yourself. What makes your heart go faster just talking about it? A hobby, a cause, a change, an improvement, and so forth?
Once you have settled on an idea, then it is time to do your due diligence. Will this action be of a worthwhile financial gain for you? Will it improve other peoples way of life in a postive manner? Is there a shortage for it? Maybe there is an oversupply that you might have overlooked.
Most of these questions can be identified and explored by running a feasibility study on them.
A feasibility study is just that: Is this project feasible? If it isn't then don't waste time and money exploring it further at this time.
If it is, well you just might have your gold mine.