There was a movie a while back that talked about what makes people happy: https://en.wikipedia.org/wiki/Happy_(2011_film)

It had some interesting ideas, and one of the things that stuck with me is the idea of your brain being a "difference engine" in that the variation is what matters. If we don't experience pain, we can't experience pleasure.

It seems a bit simplistic when stated that way, but I think there is something to it.

Another thing I have come to believe as I have aged is that our western (American especially) society places too much emphasis on happiness, in that we think happiness is (and should be) the prime goal of every human. I have come to believe that less and less, and think something like satisfaction, contentment, and purpose are much more important as life goals than happiness. Happiness is an important part of life, and is important for reaching the other goals I mentioned, but it is not the end goal (to me). I think most of us somewhat intuitively understand this, although our response is often to redefine what happiness is rather than concluding happiness isn't our end goal.

If happiness was everything, we would be much more accepting and encouraging towards hedonism than we are. A heroin addict who has a good clean supply and no responsibilities would be the ultimate dream life if we truly believed pure happiness was the most important thing.

You say "redefine what happiness is", but I'm not sure there's any "re"-definition necessary, it can just be about how you define it. I wouldn't say that the things you mention (satisfaction, purpose, etc.) are alternatives to happiness, but rather that they're particular forms of happiness. And maybe the hedonism of the heroin addict is another form.

I'm not entirely sure it's incorrect to say that the heroin addict's life isn't a valid and desirable form of happiness in theory. The problem is that in practice pursuing that type of happiness has a high risk of plunging into extreme unhappiness. The same might be said of various other forms of happiness that we see as at least somewhat less objectionable. For instance, people who do BASE jumping may find a sense of satisfaction and fulfillment from doing it, but still many people might view that skeptically as a path to happiness, because again it has high risks of bad outcomes.

I tend to think in terms of aiming for what I call "robust happiness", which means a form of happiness that's resistant to changes in circumstance, and in particular to the awareness of other people's happiness. When you're happy in a way where you can look at other people being happy and not wish to have their life or their form of happiness instead of yours, your happiness is robust in a certain sense.

>It seems a bit simplistic when stated that way, but I think there is something to it.

I think this is pretty uncontroversial and you can observe it everywhere. Even in music, if you want the beat to hit harder, take it away for a short period, and when you bring it back it will feel like it hits harder and with more energy even though it's exactly the same volume as it was before.

Though it doesn't really explain how some people are continuously more or less happy. If the brain only cared about change, you could only ever be an average amount happy. Clearly something about continuous discontent and negativity still impacts you even if it might dull.

If we don't experience pain, we can't experience pleasure..

I think there is loads of classic literature that is basically saying that in between the lines or even directly.

What I struggle with is that it’s hard to derive meaning from purpose when the best I can hope for is improving the lives of others until they are at the same level of comfort as me: struggling to find meaning and happiness.

We can all derive purpose from trying to improve eachothers lives, but if none of us end up happy, what makes that work actually meaningfull? At some point we need something that is good in and off itself. That’s what happiness is meant to be I think