According to Stanford University’s professor Sonja Lyubomirsky, you should do both. Her research proves that our ability to ‘Be Happy’ is determined 50% by your ‘set point’ for happiness (ie. genetic influence), 10% is determined by the circumstances in your life, and the remaining  40% is determined by your own attitudes, values & behaviours link.

In that article, she suggests a number of personal strategies to increase your levels of happiness, and amongst them is the following gem:

 - Practicing Acts of Kindness
These should be both random (let the dad with the crying baby go ahead of you at the check-out counter) and systematic (read a newspaper to an elderly neighbor). Being kind to others, whether friends or strangers, triggers a cascade of positive effects : it makes you feel compassionate and capable, gives you a greater sense of connection with others and earns you smiles, approval and reciprocated kindness. These are all happiness boosters.

So go crazy and start doing RAKs or SAKs every day – not only will you make someone else’s day, you will also be making yourself happier!

To learn more about Sonja’s work, head over to  http://chass.ucr.edu/faculty_book/lyubomirsky/