Ignore ideas, notice problems. If you focus on that, profitable startup ideas will come from noticing small, repeatable annoyances.
Cool ideas are the bane of startups. What you need are problems that lack sufficient solutions. Sometimes a solution does exist but not for certain groups or only at certain budget levels - that's a startup! Flow like water to fill gaps in the market.
Try to do any task on a computer and you'll find 95% of existing things suck and can be improved. You can sell these improvements. Don't worry about competition, that just means your idea has been validated. Make stuff you want to use yourself, that way even if you fail to sell to others, you're not at a complete loss. Plus you do not need to repeatedly iterate with a customer if you are the customer.
This is where some acknowledgement of the fact a lot of low hanging fruit has been eaten at this point is in order. I feel like more game changing products of this decade are not going to be Uber for X type apps but more original creations.
You might have ideas, but don't write them down because you don't think they're profound enough (yet). In that case, I'd suggest to track those ideas in an app or book. This gives you something to play with and reflect on, find patterns.
If you actually have few ideas. then that is also fine. Why do you think you need ideas? You can think about or work on other people's ideas.
The Mom Test, mentioned in the post, have a good templates on how to do research on problems your potential clients might have. First 3 chapters are good to read because they explain what should be focued on and what's artificial.
Cool ideas are the bane of startups. What you need are problems that lack sufficient solutions. Sometimes a solution does exist but not for certain groups or only at certain budget levels - that's a startup! Flow like water to fill gaps in the market.