What constitutes true happiness?

Just finished Episode 19 from Season 5 of Criminal Minds.

I loved the quote at the end of the episode:

Many persons have a wrong idea of what constitutes true happiness. It is not attained through self-gratification but through fidelity to a worthy purpose. — Helen Keller

I googled the longer quote below.

“Certainly I believe that God gave us life for happiness, not misery. Humanity, I am sure, will never be made lazy or indifferent by an excess of happiness. Many persons have a wrong idea of what constitutes true happiness. It is not attained through self-gratification but through fidelity to a worthy purpose. Happiness should be a means of accomplishment, like health, not an end in itself.”

Year - 1954. Helen Keller explains That her Greatest Disappointment in life is that she can not speak normally. 

TRANSCRIPT: " In this room sits a remarkable woman. She's Miss Helen Keller. She does not see the room, or the book she's reading. She sees nothing . She doesn't hear the rustling of the curtains behind her. She is deaf... Deaf and blind. But if you enter a room she will know it. Your lightest foot fall will tell her you are coming. It will even tell her who you are, if she knows you. As she knows her old friend Polly Thomson. Polly has been with Helen forty years. For half of these she has been Helen's only companion. Helen's eyes and ears on the world. She talks to Helen with a finger system in which each letter has a sign...like this. Reaching out beyond her dark and silent night, Helen depends most on touch. Two other senses remain. There is taste and smell. Scent... the scent of objects and places and people tells Helen much that we learn with eyes and ears. But her hand is her chief link with the outer world, with Polly, with Anne the part time helper. With everyone she encounters. With her hand she reads Anne's lips. She answers with her voice. It is an un-natural voice, and is her great sorrow. For all her years of effort Helen has never learned to speak clearly. This isn't strange. For since she was a baby she hasn't heard a word spoken nor seen lips forming one. But let Helen, with Polly's help, tell you. (Helen speaking) : "It is not blindness or deafness that bring me my darkest hours. It is the acute disappointment in not being able to speak normally. Longingly I feel how much more good I may have done, if I had only acquired normal speech. But out of this sorrowful experience I understand more clearly all human striving, thwarted ambitions, and infinite capacity of hope."

J.F.