This article in Time doesn't say anything that research hasn't known about for years, but it does it in a very accessible way. So I recommend to anyone that it is a good, short, skimmable, read.
The purpose of the article is to explain why we tend to have an optimism bias, from an evolutionary perspective and neurophysiologically. Then it discusses the effects of this bias on typical lifestyle choices, which is why I am recommending it.
The attached article on 20 ways to be more happy is a good addition. It has some practical steps (some easier than others) on how to evoke the optimism bias and get a little happier. Some of them are short term, but have really solid research behind them.
For example the finding that smiling and laughing are bi-directional has some strong research in support. Not only do we smile and laugh when we are happy, but even a forced smile or laugh can actually make you happier. Maybe not by orders of magnitude, but over time it can have an effect like mindfullness where the extra happiness because ingrained.
Some of them are harder. For example "Marry Happy." Everyone goes in thinking they are happy, but the stats show that unexpected things get in the way. Often disagreements on spending habits and saving habits, which never even came up beforehand.
But if you combine them, so think happy, smile a lot, be optimistic, and marry someone that makes you happy, they all support each other in one huge virtual cycle that will make you happy as heck and the rest of us jealous.