Every man has a different perception of what their state of happiness is. Happiness for one man can be sorrow for another. The stories of Aristotle debate the idea of happiness and how to reach the state of happiness. The Bhagavad-Gita is also a story that tells man how to live and how to reach his state of happiness. The two stories have some of the same ideas on how to live life and how to truly reach a true state of happiness. Happiness is a state that is different for every man.
Aristotle believes that everyone carries out actions in attempt to get some kind of good out of each action. Getting good out of an action, he believes, is what makes one happy. The quote "The statement that the happy man lives well and acts well, too, is in harmony with the definition of happiness" (Aristotle's Nicomachean Ethics page 5) demonstrates Aristotle's view. Every man wants to be happy no matter how he reaches his happiness. Happiness is the goal of every man, no matter how he reaches it, every man wants to be in their state of happiness. Therefore, every man should do what makes him happy, no matter what it is. If being a professional baseball player makes him happy, then that is what the man should do. If saving lives is what makes him happy, then that is what he should do. Aristotle's idea is that the man should do what he wants and make his own decisions, good and bad, for the reason that he is trying to make his life better by doing what will make him happy.
The Bhagavad-Gita states that people should carry out and fulfill certain actions because it is their duty and it is the nature of the soul to perform these actions. While performing actions the Gita believes that one should have no particular concern of the outcome, whether it is success or failure. In The Bhagavad-Gita Arjuna is reluctant to fight in battle because if he were to fight he would be going against his own kinsman.