All these are rooted from one thing: why should I give you my money?
The simple answer is because you give me something else in return.
—But I can't just pay for anything, it should be something which I real need, something which if I can't get it a part of my life will be miserable (pay or be miserable).
To refine this answer then, one pays you so as you can feed a need, solve a problem, full stop and nothing else.
Your business idea then should be rooted from here.
Your business is going to be the solution to this problem one face, so to come up with a business idea literally means to come up with a solution for a problem.
There are two major ways to come up with a solution (business idea) which is more likely to be successful:
1. If there is no existing solution come up with your own new solution (innovation)
2. If there is an existing solution use it but on places where it is not easy to get it.
By this we mean if a solution is not easily available because of high cost (make it cheap), it is far away (make it closer), it's annoying but people want it (make is easy), and more other forms of unavailability (make them available)
Something to note: You can't think up business ideas, you have to know well and prove there is a problem otherwise it'll be for nothing; that's why it's called a solution, you can't have it for nothing.