Jewish Law instructs us that upon entering the month of Adar we should increase in joy. In other words, it is a Jewish obligation to be joyous during Adar. In truth, joy and happiness are elemental to serving God all year round, because joy and happiness motivate us and bring vitality to our service and the mitzvahs that we do.  Happiness isn't that simple. Happiness is a frame of mind, and it's deceptively difficult to achieve - and maintain - that mindset.