I noticed another review, which gave "The Joy Diet" a single star and noted that no single menu or diet will grant you happiness. And I agree with the notion that happiness-in-a-jar isn't realistic, but I don't see "The Joy Diet" as a quick solution.
Reading "The Joy Diet" I literally smiled and aha'ed a lot. I already know a lot of the issues, that Martha Beck addresses in the 10 menu items. I know that when I am stressed out, it is a good idea to have a time out and do nothing or that laughter is a great pick-me-up. These are just things that I keep forgetting - and therefore sometimes need to be reminded about.
The humorous packaging is hilarious and down to earth, which I really appreciate until most self-help books written by more or less pompous Messiahs.
So rather than happiness-in-a-jar I see "The Joy Diet" as a happiness-buffet with different inspirational menu items to get a step closer to happiness.