It is believed that to avoid developing or worsening myopia, we must rest your eyes every 30-40 minutes. The general advice is to look out of the window or take a break outside.Does this really help?

I'm just speaking from my own personal experience. I practice this and have perfect eyesight since young. At home, I would take breaks even if I was just doing homework (haha... kind of like an excuse to walk around the house and stare out of the window). Just outside my house used to be a big field, so I kind of believe in the idea that looking at green stuff helped. Generally, I think taking frequent breaks is a good habit to cultivate. It not only rests the eyes, also gives our minds a break too! :)