The secret of happiness is truth.
That is to say, if you want to be happy, you must not feel guilty, and if you don't want to feel guilty, then you must evaluate your actions from a moral perspective, and to think about right and wrong you must seek the truth.
If instead you are seeking power and status, you may grow wealthier and advance to higher positions, but money does not buy happiness (although money can certainly buy pleasure).
Pleasure is a temporary emotion, while happiness lasts.
Consider the things you like to do; you are always concerned with quality. If you like sports, you remember the great athletic performances; if you make things you remember your finest products; if you collect, you are fond of your best specimens. But to make these judgments of quality, your mind must be attuned to the truth. The greater your expertise, the more you are aware that utter honesty is necessary to find the best of human attainments, and the more disappointed you are on discovering a fraud or a shoddy job passed off as a good one.
In short you are most attentive to truth when you are pursuing your most highly valued activities.
The search for truth lets you understand the challenges facing humanity and makes you a voice for a better stewardship of our planet. You will be happier knowing that your political voice is not based on self-interest but on a truthful appraisal which will benefit future generations.
Power, on the other hand, is a fickle master; as soon as your power starts to wane, your opponents take advantage of your weakness and cast you out. You may have success and pleasure, but happiness will elude you.
Seek the truth in all you do and you will be virtuous and happy. The knowledge you gain will light your way through the darkest troubles. Truth, like virtue, is its own reward.
The secret of happiness is truth.