I can code, but can't get ideas. Those who made multiple apps, how do you do it?

The development part is not a problem to me, I can pretty much do it with no trouble but when it comes to ideation, I go blank.

Sure, I've heard many things such as: "Solve your own problem", or "solve a very small problem", but when I do have an idea, I research the market and I see that the solution already exists, and sometimes many solutions, no matter how unique i thought my idea was, it got taken already and it is doing well.

So how do you guys do it? How do you come up with such great ideas?