Aristotle tells us that happiness is the reward of virtue. That is, in the Aristotelian thought happiness is an end itself and we practice the virtue to achieve happiness. But what is happiness in this thought? The soul is the first motor mobile according to Aristotle in his book "About the Soul"; the soul has his own faculties as the locomotive, nutritional, reproductive. Happiness represent a state of optimization of these faculties, or in other words the "welfare accompanied by virtue" (Rhetoric Book, Aristotle).
To achieve happiness we have to make choises and with the choice the virtue arises. In other terms, we seek happiness because happiness is the natural desire of the soul and from these the virtue is born.
This reasoning responds to the "field" of the soul or "morality". The moral discourse is about virtue and good manners, ultimately the moral studying is about everything that we "value" to be "naturally" happy.
But the desire for happiness is a selfish desire, morality is not about the problem of good and evil. The thought and the works of Aristotle, ultimately the Greek philosophical ideas, are the basis of the Occidental morality.
But then what is spirituality?
When we speak of spirituality we talk about perfections. God is the source and origin of all the perfections that we observe in the creation and God's desire is to radiate his perfections to creatures. The spiritual gifts are perfections.
When Christ, and this is the difference with the thought of Aristotle, says "be perfect as the Father is perfect" he call us to live the spiritual gifts we inherit from God, to look for what is correct and the best, to perfect us, to help our neighbors and to improve the world, "to live according to the spirit"; not to seek our own happiness, to this last Christ calls it "to live according to the flesh".
The spirit identifies itself with the desire for the good, the soul with the desire for happiness.
We live according to the flesh and we practice the sin or we live according to the spirit and we act for ethical rules (the golden and silver rule), Christ teach us.
Through the "desire for good", which is the will of God, we perfect ourselves and we resemble him, we become perfect as the father is perfect. In this consist the spirituality.