Based on a research on nuns (yes, nuns! ... to minimize confounding variables, the research says), this is the secret (excerpt):
The belief that we can rely on shortcuts to happiness, joy, rapture, comfort, and ecstasy, rather than be entitled to these feelings by the exercise of personal strengths and virtues, leads to legions of people who in the middle of great wealth are starving spiritually. Positive emotion alienated from the exercise of character leads to emptiness, to inauthenticity, to depression, and, as we age, to the gnawing realization that we are fidgeting until we die. The positive feeling that arises from the exercise of strengths and virtues, rather than from the shortcuts, is authentic.
The trait of optimism helps explain how a single snapshot of the momentary happiness of nuns could predict how long they will live. Optimistic people tend to interpret their troubles as transient, controllable, and specific to one situation. Pessimistic people, in contrast, believe that their troubles last forever, undermine everything they do, and are uncontrollable. Optimism is only one of two dozen strengths that bring about greater well-being.
We need a psychology of rising to the occasion, because that is the missing piece in the jigsaw puzzle of predicting human behavior.
Read more about it here.
Somebody I loved told me once, "Can you tone down your sunny you please? You make me feel worse."
It hurt, very much, considering that my choice to be positive is a choice borne out of the pain and struggle of rising above negativity, not just a blind adoption of some Pollyanna-ish philosophy.
Of course I didn't "tone down the sunny me"!
I said goodbye to him instead.
I'm glad I did.
It wouldn't have worked out for us in the long run; he would have been a drag, to say the least.
He would've significantly shortened my life too, haha.