Unfortunately, this isn't so much a "manual" as an interpretive digest of various studies which had results suggestive of their subjects' feelings of well-being. Each of the 100 sections has the same structure, a title like "Do Things You Are Good At", a few sentences explaining the concept of the title, a couple of paragraphs of a personal or societal vignette (like the one in the "Get A Good Night's Sleep" section that noted that productivity rose 3% on Tuesdays in the fall of 1998 in the North-East versus previous years, apparently due to Monday Night Football starting an hour earlier that season!), and very brief summary paragraph from some formal research study that carried the theme forward.
Most of these 100 "secrets" are pretty much no-brainers, like "Don't Blame Yourself" or "Exercise" or "Turn Off The TV", but others are probably not top-of-mind like "Your Goals Should Be Aligned With One Another", "Keep Pen And Paper Handy", or "Believe In Ultimate Justice", where the explanatory copy is useful. Each section is between 1 and 1½ pages, so this is a quick read, and as varied and non-preachy as it is, it's enjoyable. How useful, ultimately, it is for a "Grumpy Gus" like myself is debatable, but I figure that if I pick up a few pointers, who knows ... maybe next thing I'll be using perfect belief to manifest a huge Lotto prize win into my life! Hey, I have a ticket, it could happen!
The 100 Simple Secrets of Happy People does seem to be out-of-print at the moment, but there are lots of used copies out there, with Amazon's new/used offerings ranging from a penny for a "good" copy to a buck for "like new". Frankly, I got this via a clearance sale at Barnes & Nobel's web site. It's not a bad book to have sitting around (a top-of-the-toilet classic?), so if you see it for cheap, go ahead an pick up a copy, it'll make you feel better, really!