I enjoyed The Happiness Project by Gretchin Rubin. Rather than trying to be happy by changing geographies like the Eat Pray Love approach, Gretchin just tried to change one thing a month for a year to be more happy while staying right at home.
It is a light hearted but useful book. It is practical and never preachy. Do give it a go if you are feeling that you should be happier than you are. This is not a book to help medically depressed people or people who are grief stricken – it is for ordinary people who just need a tad more joy in their lives.
I do like her one minute rule (but don't do it very well). The rule is that if you can do something in a minute or less, do it right away and don't postpone it.