What caused sadness and stress?

Quite often sadness is brought about:

By constantly comparing yourself with others.
(Adults love to compare. Stop it or I will start comparing you.)

By remembering old things and occurrences.
(What past have past. Since you don't like to study about others history, then don't dwell too long on yours.)

By being arrogant in our actions.
(This will distant yourself with others. Friendly is what bring everyone together.)

By constantly wanting something we don’t have.
(After you want it, you will ask for more. You will never be satisfied.)

Constantly striving for the material thing or people or things that we think will make us happy.
(Like those youngsters kept claiming that those idol is their husband, is their only love in life. All those who wanted this things in their life when it is only a want and not a need. I don't know how long that passion will last when they got it. This reminds me of abandoned pets.)

By getting tired and irritated with others and their actions.
(Why do you care about others? Do you live for them or do they live for you? No one can change others. Only you can change yourself. Changing others will make you seems like that is your job but without salary.)

In a nutshell by forgetting who we are and living a role of what we think we ought to be or how we think others want us to behave.
(Often we did forget who we are by pleasing others, by getting really affected by others. Please BE YOURSELF. You will be living happier and more fulfilling this way.)

You already know how to live a happy and contented life; the only trouble is you have either forgotten it or your current thinking is ignorant of it.
(Yes! Many have forgotten. I once had the same mistakes. But by sitting down quietly and reflecting on my life, only then I discovered that I am off track. Time to get back on track. Of course it is not easily said than done but after all control is within ourself, we control our own mind. Tell me which part of you are control by others? Seriously, if you think clearly, there is none ok! Stop pushing the blame on others.)

Your state of mind is crucial. It is the key that unlocks the door to happiness.
(Take it and be happy, leave it and live miserably. Choose it yourself. No one is forcing you but yourself.)