Some interesting research on happiness is highlighted by Tasty Research.
In a nutshell, it suggests that while gains in happiness from changes in circumstance are fleeting, gains that are achieved through our own actions are lasting.
For example, the happiness that comes from a windfall like a lottery win generally does not last. But the happiness that comes from taking action to become fitter is more permanent.
All these studies need to taken with grains of salt as social science research is always pretty provisional and always open to many interpretations. But this does fit well with my own experience and what I have observed in others.
Though the original paper doesn’t look into this, there are schools of thought that say a large component of happiness comes primarily from your own view of yourself. So if you see yourself as someone worthwhile, someone who has overcome challenges and fears, has worked and achieved something of substance, that will make you happier.
Taking actions outside of your past patterns of behaviour can change your view of yourself, whereas changes in circumstance generally don’t have that impact.
This also has a bearing on the topic of welfare, which can keep people from material want but does nothing for their self-esteem or happiness.
The original paper on which this is based can be found here.