Very true, most people are constantly grumble about their lot and instead if they used their energy to better their lot, they could see some positive changes in their lifestyle...

Most of the people fail to  see their own  blessings. instead they see others virtues..

I think healthy discontentment is the first step to progress. It is ultimate thirst to know and understand. The psychological concept of 'pigeon of discontentment' exactly talks about creation of healthy discontentment within personality to progress. 

A healthy discontentment should make you walk towards your development. This is possible only by knowing your Niche and your own strengths. Because all are having some uniqueness or other. Nobody is useless.

True. We are all unique with some specific hidden talents. But most of us hesitate to look within us. We prefer looking outside. That is our general nature.  Those who look within and realize their strength make life a celebration.

Weaknesses are to be strengthened and strengths are be cultivated and taken to newer heights. This is possible only by seeing in to ourselves  and identifying the hidden niche features which are lying unseen and un utilized .