While the other two answers see Rousseau, I see Rudyard Kipling and Ralph Waldo Emerson.
To me, this poem has a vision of happiness very much like that of Kipling's "If." He says that a happy man doesn't let his passions rule him, doesn't care what rumors there are about him, and doesn't envy anyone else. Those sound very much like Kipling's "stiff upper lip" criteria for being a man.
This also reminds me of Emerson, who says that being true to yourself only is what makes you happy and properly human. This says that a happy man is one who does not serve another's will and doesn't care what others think of him.
So, that's what this poem says to me.
The previous post's inclusion of Rousseau is well placed. For Wotton, the essence of a happy life is the sense of autonomy that is enhanced through an individual's actions. The idea of being free, possessing liberty, and acting in a manner that enhances both represents the essence of a happy life. Continuing the Rousseau line of logic, the conception of freedom offered is one where a pure sense of self love is apparent. This notion of amour propre is one where individuals act and carry themselves with a sense of centered action. They act in the spirit of not using elements to means to ends, but rather as ends in their own right. This helps to create a realm of action where individuals are in control of their own sense of internal good. Throughout the poem, the implication is that happiness can only be achieved when individuals act in accordance to their own concept of freedom and autonomy.
This is a lovely poem by Sir Henry Wooton on the theme of simplicity and how it can bring happiness. 'Man is born free and is everywhere in chains' is a famous quote and it is easy to see why it ties in with this poem and the idea that mankind is the architect of its own unhappiness. It is a timeless theme and one which has great relevance today in these troubled times of debt, unemployment and the misery that overspending on material things has brought. Wooton is saying that the truly happy man is not shackled in a quest for possessions by keeping up false appearances, flattering or lying to those,for example bosses, we don't like, signing our lives away for tawdry valueless things like flashy cars or clothes that will make others envious of us. Honesty he says can only be practised by those with nothing to lose - those who have not built the foundations of their lives and homes on the false promises of superfluous roles and jobs. Such peoplehave to 'cow-tow' to the regime of others. True frinds, God and a simple life are the cure to worry, anxiety and are the route to real happiness.
In Henry Wooten's poem "What Makes a Happy Life" he expresses that a man who is his own person not controlled by others is a happy person. There is evidence in the poem to suggest that man is altered and controlled by the state. However, if the person can continue to act on freewill he can find his happiness instead of one which is constructed for him. The person also finds happiness in the value of simple pleasures such as a good book or spending time with a friend.
He shares that a person who is prepared to die can live happily as he does not have to fear his death. The person has chosen his own destiny.
In addition, he addresses how not having ambition may lead the person no riches in the sense of material items, but it will also not cause him to have the anxiety brought on by drive and ambition. (Last part)