1st chapter of Anupam Kher's book The best thing about you is YOU is titled as - We all are Unhappy. He concludes the chapter as - Happiness can not come solely come from external sources. First of all we have to discover the concept of Knowing Yourself and being Yourself.
Being yourself means who? As a body or as a soul? As long as we consider self as a body his chapter title will remain true. The moment we consider self as a soul we will be on a path to achieve his last line.
Our unhappiness starts with our confusion of self as body or soul !!Our wrong belief about the self is the cause of our unhappiness.
Know your self is not about knowing your nature and habits or anything about the body but its about knowing your true form as a soul.
'I' should go with soul and not with body.