When my wife and I were dating, we discovered that we had different takes on happiness. She felt that being happy was a goal in itself, while I felt that consistent happiness is an unreasonable expectation, that as we move through life we are sometimes happy and sometimes not, and that to seek happiness will only yield frustration and disappointment.
While I was in Israel a week and a half ago, I was taking an evening stroll by the beach in Tel Aviv, when I encountered a group of "Na Nachs," a sub-sect of the Breslover Hasidim who dance through the streets of Israel blasting music from vans, to the amusement and/or chagrin of all around. One of them handed me a booklet titled, "Simhah" ("Happiness"), which includes a selection of quotes by Rabbi Nahman of Breslov on that very subject. On the back is the following piece of wisdom, which seems to be the credo by which the Na Nachs live:
והעיקר להיות בשמחה תמיד, וישמח עצמו בכל מה שיוכל, ואפילו על-ידי מלי דשטותא לעשות עצמו כשוטה ולעשות ענייני שטות וצחוק או קפיצות וריקודים, כדי לבוא לשמחה שהוא דבר גדול מאוד.
"And the principal idea is to be always happy, and that one should apply all his ability to make himself happy, and even by means of nonsense words that make one as a fool, and to engage in foolish matters and laughter or jumping and dancing in order to come to happiness, since [happiness] is a very great thing." [Tanina 48]
I must confess that, while being happy is clearly important and we should seek those times of joy, I can't say that I think it's a good idea to strive to be always happy. We need space in our lives for other emotions and states of mind: sadness, anger, love, grieving, seriousness, and so forth. To attempt to be always happy is to court frustration.
Look forward to the happy times, but remember that we need the other times as well; that is what makes us human.