Well, I feel, it is our perception of the event, thing, untimely (or timely) circumstance that allows unhappiness to linger on in our lives. Therefore, Our happiness can be altered per Our Own power...our mind. If we learn to seek True & Honest understanding, be Strong enough to accept Our lives (and who we are), and lastly, be Courageous enough to step out of our past (whether it be 1 minute, 1 month, or 1 year --it's the past) and ever so Boldly/Fearlessly reach for our future; Unhappiness stands not a chance to exist.
Happiness can be obtained, in life, by simply asking yourself whether you are happy. Do this and you will cease to be so.