Socrates, and later Plato who seemed to continue Socrates' philosophies, believed the most important thing for a human was to live a "good life", or Eudaemonia in Greek. "Good life" in this context refers to a life of virtue, ethics and looking out for one's soul.
Whilst this was prominent in many of Socrates' accounts it also featured in Plato's description of Socrates' legal battle in Apology, a term which means defense-speech rather than the mordern apology. Many theorize that this was not a true historical account and as such this philosophy could well have been Plato's own as well.
Eudaemonia can be seen in many of the Christian philosophers and philosophies. Specifically, Thomas Aquinas talks of the 4 virtues which leads to eudaemonia, or a happiness or fulfillment derived from being guided correctly by a divine power.
agora.stanford.edu/agora/cgi-bin/article.cgi?library=segvic no longer exists
wsu.edu/~dee/GREECE/PLATO.HTM no longer exists
https://en.wikipedia.org/wiki/Apology_(Plato)
