Both a concentration camp prisoner and world-respected author and
psychotherapist in his lifetime, Viktor Frankl writes the following
advice about happiness:
"Again and again I therefore admonish my students in Europe and
America: Don't aim at success - the more you aim at it and make it
a target, the more you are going to miss it.
For success, like happiness, cannot be pursued; it must ensue, and
it only does so as the unintended side effect of one's personal
dedication to a cause greater than oneself or as the by-product of
one's surrender to a person other than oneself.
Happiness must happen, and the same holds for success: you have to
let it happen by not caring about it. I want you to listen to what
your conscience commands you to do and go on to carry it out to the
best of your knowledge. Then you will live to see that in the
long-run - in the long-run, I say! - success will follow you
precisely because you had forgotten to think about it."
Of course, the important part is the "...in the long-run..."