There was one line that I read before somewhere. "Human learns to be human through human interaction." Not sure if it's true or not. But, I supposed one way to achieve being "normal" is by accepting society, following the norm, submitting to peer pressure, etc.
Basically, remove any kind of individual thinking in your head and simply think like "everyone else" is thinking. Don't bother disagreeing with mainstream worldview. Always seek approval from other people before making individual judgment. Follow all social media trends. Join mainstream religion. Do what everyone else is doing and then you can live the rest of your life on autopilot.
Thus, you shall become "normal".
(Please don't take what I said seriously. I was being sarcastic, lol.)