If you loved The Happiness Project, then Happier at Home will be for you. It serves as a good refresher as well as containing a few new ideas. You do wonder, though, just how many more books can be written about the author's quest for happiness!
The book does contain some really important ideas (most of which were in the original book) – such as:
The days are long but the years are short
The task you haven't started is the most wearisome
No one else can make you happy