Ask HN: How do you come up with creative, original ideas?

Sam Altman said that "original thinking", ability think independently is one of the best predictors of founder success.

I'm good at learning and understanding things, but bad at inventing my own original interesting ideas, and I want to get better.

How do you come up with new insightful ideas? Did you learn some mental tools, skills, or habits that helped you get better at this? Are there any good books on creativity/invention/innovation that can help?