I haven't read any of the site but recognised this theory immediately. It has purportedly been shown to rest on an abuse of mathematics: http://www.the-scientist.com/?articles.view/articleNo/36910/title/-Positivity-Ratio--Debunked/
Author of the site here. Totally agree.
The evolutionary psychology may or may not be correct. I think there's some kernels of truth to it. But the mathematical model is crazy insanity, and I'm somewhat ashamed that I needed someone to point it out to me, especially considering that a brief look at the studies done which measured and correlated positivity ratios found 'dividing lines' all over the place, from 2 to 6 (http://happierhuman.com/losada-ratio).
I found a website called Happier Human. It's about how to become and stay happier. I've trawled through it. Here are the best posts in my opinion:
[Meditate]. Don't [worry/overthink/fantasise/compare]. [Disregard desire]. [Motivate]. [Exercise gratitude]. [Don’t have kids].
[Buy many small gifts]. [Trade some happiness for productivity]. [Set] [happiness goals]
If you've found any other happiness interventions on any website, please share them.