>> don't hinge your happiness on something as random as an interview decision

This is easier for senior folks. At some point you just know the rejection was a failure of their interview process and not your ineptitude. I have failed several interviews at different companies where I was one of the best people _in the world_ for the job due to my domain expertise. It's a roll of the dice for everyone, but earlier in my career I did not take rejection well. Now? Honeybadger don't care.