- a loved and loving partner, a sane and fulfilling sexuality
- enough income to not have any substantial worries about the future
- absence of other justifiable existential worries and anxiety about the future such as cataclysms, threats, oppressive social, political and work environments, political instability, etc.
- a decent amount of recognition in work or private life (one of them suffices, both are optimal)
- good mental and physical health
Beneficial is also frequent contact to about 3-4 close friends.
That's what I've gathered from what I've heard on the Net during the past 20 years or so. If any of the above is missing, the life will not really be good.