Happiness, as defined by Einstein

I felt like writing about happiness but my state of mind was not in the best of mood to write about it.
I was wondering how we could define happiness.
Happiness which comes from "Happy" means "feeling or showing pleasure or contentment."
Now, the question is, How can one be happy or how can one feel or show pleasure or contentment?

I think the answer was written on a piece of paper back in 1922 by arguably the smartest man to ever live, Albert Einstein.
The story goes that, Albert Einstein was delivered a message by a bellboy and he (Albert Einstein) did not have a tip to give to the bellboy so instead, he(Albert Einstein) wrote a theory of Happiness and gave it to the him (bellboy).

This artifact (piece of paper) recently sold for 1.5 million dollars but the message on it was priceless.
It read, "A calm and modest life brings more happiness than the pursuit of success combined with constant restlessness," Mr. Special Relativity himself says a peaceful mind and a peaceful life is the Key to Happiness.

I know this goes against most of our ideas about happiness in our society but let me explain this with an example; Let's assume you need a new phone, and you constantly work hard in getting it. One day you got to buy this new phone and you are happy. Is it the new phone that made you happy or  the release from the craving of getting a new phone?

Of course, it is the release from the craving of getting a new phone. Phones do not give happiness . We often think that the awards, accolades, items we purchase can make us happy but after Jim Carrey said, "I think everybody should get rich and famous and do everything they ever dreamed of so they can see that it's not the answer."
I think we should reconsider how we define happiness and take note of the wisdom from the great Albert Einstein.
Let's try to live a calm and modest life, that is if we want to be happy.