1. The spontaneous idea: It hits you when you’re in the shower, driving in your car, talking with friends, or doodling during a meeting. The dots suddenly connect in a new way and you have an epiphany ... your sudden insight is surprising and exciting, and the value of this new idea seems obvious. You can’t believe nobody else has thought of it before.
2. The insider idea: Maybe you've spent the last seven years building enterprise software for airlines, and you've noticed some voids in the product stack or issues with how your company brings it to market. You point these deficiencies out to your bosses, but there are other company priorities and nothing changes. Or, say your company pays vendors a lot of money to do some work, but nobody ever seems happy with the results ... and you see a way to do it better for less.
3. The deliberate idea: In this case, you aren't starting with a business idea. Instead, you’re starting with a desire to create a new business and become an entrepreneur. You may be ready to quit your job and go for it whole-hog, or just start it on the side of your desk ... but you’re looking for the right business idea to pursue (which could be a business related to your work environment or industry.