Fabrice Grinda is becoming an expert on happiness (there I contribute to the trend :)), and here are some thoughts on what it takes to be happy:

1. Don’t equate happiness with money.
2. Don’t commute.
3. Exercise regularly.
4. Have lots of sex.
5. Devote time and effort to close relationships.
6. Pause for reflection, meditate on the good things in life (in other words be grateful).
7. Seek work that engages your skills, look to enjoy your job.
8. Give your body the sleep it needs.
9. Don’t pursue happiness for its own sake, enjoy the moment.
10. Take control of your life, set yourself achievable goals (in other words have goals).
11. Have an optimistic attitude and outlook on life.

On a more serious note, a previous post by Fabrice refers to a recent Harvard Magazine article, dealing with the issue.