How does he define happiness or happy? A definition is not offered at the beginning of the interview, but we do find a hint later:
Helen: So, the main confusion is that people look at their problems from a secular attitude, saying to themselves, “My life should be happy here on earth” rather than looking toward the life after this one. Is that so?
Fr. Thomas: Yes. I would also say that not only do people look at life secularly – which I guess would mean with no relationship whatsoever to God – but I think it’s also true to say, especially nowadays, that many people look at the world in a falsely religious way. Not necessarily just secularly. People think that God exists to make our earthly life “happy,” to take away all suffering and pain, to do whatever we want Him to do, that all we have to do is “name it and claim it” and God will give it to us, no matter what it is — health, a good job, a good sex life or, for example, how the human genome project is described. I read it recently on the front page of the New York Times. The director of the project said: “Our purpose is very clear: it is to live a longer, happier, more pain-free, healthier human life before we inevitably die.” Well, many people think that’s a good program. Many religious people think that’s what God is trying to do, too — to make us live a longer, happier, healthier, better, and easier life…
The accumulation of various goods, but not the eudaimonia of Aristotle or Aquinas.
The full interview.
Related:
Something on those happiness studies. [Subjective] satisfaction vs. fulfillment based on objective meaning?