Ideas, like anything else take practice. I have a few friends that say “I don’t have any ideas” or “I’m not technical enough”, and my usual response is, that there are whole worlds of undiscovered business ideas out there (and even more that are already working, that just need to be tweaked for a different market or location). They don’t all require being technical either.
I advise them to buy a little mini moleskin notebook and write down three business ideas a day, without regard for size, feasibility in execution, etc. Just write down ideas. It trains the brain to always be on the lookout for ways that you can trade your skills for money. Eventually you’ll stumble on something that excites you, is something you can manage, and has an addressable market with a real need.
Now, I find no one takes that advice. Usually because “I don’t have ideas” is a rationalization for sticking with the status quo. I don’t knock that mindset by the way. Building a business is a scary proposition and it takes time to build up the motivation to take action, and some will never get there…and again, that’s perfectly OK.
If you’re sufficiently motivated, not having ideas isn’t the problem, ideas will be all over the place. Like @Layla said, the problem is filtering those ideas based on execution risk and potential upside (however you want to define those two dimensions).