It is a commonplace among moralists that you cannot get happiness by pursuing it. This is only true if you pursue it unwisely. Gamblers at Monte Carlo are pursuing money, and most of them lose it instead, but there are other ways of pursuing money, which often succeed.
So it is with happiness. If you pursue it by means of drink, you are forgetting the hang-over. Epicurus pursued it by living only in congenial society and eating only dry bread, supplemented by a little cheese on feast days.
His method proved successful in his case, but he was a valetudinarian, and most people would need something more vigorous. For most people, the pursuit of happiness, unless supplemented in various ways, is too abstract and theoretical to be adequate as a personal rule of life.
But I think that whatever personal rule of life you may choose it should not, except in rare and heroic cases, be incompatible with happiness.
Man is an animal, and his happiness depends on his physiology more than he likes to think. This is a humble conclusion, but I cannot make myself disbelieve it. Unhappy businessmen, I am convinced, would increase their happiness more by walking six miles every day than by any conceivable change of philosophy.