"The best understanding of eudaimonia is not that it's some point reached; it's not some transient state, but a veritable form or mode of life. It's life of a certain character and stripe, properly described as a flourishing life." - Daniel N. Robinson, The Great Ideas of Philosphy, 2nd Edition, Course GuidebookHow to obtain eudaimonia was a common point of discussion in early Greek philosophy. Aristotle proposed that eudaimonia was obtained when we fulfilled our essential nature as human beings. This can be better understood by examining animals. A fish cannot fulfill it's nature when it's out of water. This is where we get the phrase "a fish out of water". A fish needs to be in water, a bird needs to fly, a horse needs to run. Likewise, we are only happy when we can fulfill our essential nature.
Philosophy has never been able to definitively answer what human nature is, but the gospel of Christ has the answer. It teaches us that our essential nature is divine. We are children of God, and as children we have the potential to become like him.
The gospel of Jesus Christ also teaches about a concept similar to eudaimonia called the abundant life. "The abundant life is a spiritual life" which promises rewards of happiness and prosperity (though people disagree on whether prosperity includes a promise of material wealth).
Despite it's teachings on the abundant life, I don't think that the gospel adequately explains why righteousness makes us happy. Why does doing good satisfy our conscious? It can't be purely due to the delayed gratification of eternal life. The other common answer is that the Spirit of God endows us with happiness as a reward for righteousness, but if we are to become like God then we must be able to feel that on our own.
Aristotle's teachings on eudaimonia is the answer. Righteousness makes us happy because it fulfills our divine nature as children of God. This also bring a new level of clarity to the 13th Article of Faith:
We believe in being honest, true, chaste, benevolent, virtuous, and in doing good to all men; indeed, we may say that we follow the admonition of Paul—We believe all things, we hope all things, we have endured many things, and hope to be able to endure all things. If there is anything virtuous, lovely, or of good report or praiseworthy, we seek after these things.Eudaimonia. The Good Life. The Abundant Life. Eternal Life.