Best, and most scientific [0] book in this regard: &quot;the emotional life of your brain&quot; by Richard J. Davidson.<p>One of the TLDR: the feeling of being happy and being sad are not the same brain-function with a sign reversed. Just because you&#x27;re not happy doesn&#x27;t imply you are sad and vice versa, just because you&#x27;re not sad doesn&#x27;t imply you&#x27;re happy.<p>You have to train not-being-sad and being-happy independently!<p>[0] every hypothesis was experimentally tested!