I've come upon a cropping of Happiness books, self-help if you will, as I've been checking things out at the library. I find studying this topic so interesting, as the advice blends, overlaps, and sometimes conflicts (usually based on whether the author cites science or their own anecdotal viewpoint).
The two I've enjoyed the most are by the author Sonja Lyubomirsky. I think hers were the most compelling simply because it was all the compilation of and ways to use results of scientific studies. She cited her evidence throughout and I never noticed a "seems like" or "should be" in the wording...except when dispelling myths.
If you are a fan of non-fiction like I am, I'd recommend her two books. I really think you should read all of the background, but in case you are curious, I'll share the list she compiled mid-book.
Again, I'd recommend her books because they delve into the how of making these practices part of your life. I've spent more time reading the details of some of these chapters than I have entire novels. It's interesting stuff.
Some of my favorite books/information are what I have learned from Malcolm Gladwell. I enjoyed that she brought up his findings and even added to them by exploring how we get the motivation to put in the 10,000 hours he teaches us about.