Balance.

As human beings, we must not seek happiness.. but balance. Balance in life is so important. Even in nature, there is life but there is also death. We must thrive on the good and the bad. The second part of that statement probably doesn't seem very appealing. But! It is necessary. There will always be good and, more noticeably, bad. There will always be ups and downs, highs and lows, good days and terrible weeks, hard times in life and times where we have our heads in the clouds. This is all just an act of human nature. If we didn't have emotion we wouldn't feel any of these things. Or if we lived in a world where only good things happened.. no balance. So, in result, there would never be true peace or happiness. We'd always be searching for something more. It is simply an act of human nature.
Personally, i thrive on trials. Simply because i know from personal experience that there is always something to be learned and gained from even the toughest of situations. Had we not had the experiences we did we wouldn't quite be the person we are today. Maybe you're not happy or pleased with yourself that you did something, or maybe you wish you had said something different. But guess what, you didn't. End of story. There's no changing it. You can't reverse the hands of time. So you have two options. One: sit and waste your energy regretting it. Or, two: Accept it and move on. Because in that exact moment in time, whatever you did or said was EXACTLY what you wanted right then. Perhaps now you would react differently, but then you didn't learn anything from the situation. We are constantly changing. That is the beauty in life. So if you can accept change, truly live your life with no regrets, and glorify in your hard times as well as your happy times, you will have found personal balance in your life a lot easier and sooner than others, and you will reach complete, utter happiness. :)
~Lace:)