Comments
Antidepressants do actually seem to work, and I think it's weird that people forget/neglect this. See Scott's review here and more recent writeup. Those are both on SSRIs, there is also Wellbutrin (see Robert Wiblin's personal experience with it here) and at least a few other fairly promising pharmacological treatments.
I would also read the relevant Lorien Psych articles and classic SSC posts on depression treatments and anxiety treatments.
Since you asked for the meta-approach: I think the key is to stick with each thing long enough to see if it works, but also do actually move on and try other things.
In my opinion for a person that has it "pretty good" objectively, the limiting factor on their happiness is what the Default Mode Network (DMN) is (or is not) doing.
I think that at least part of it, can be roughly equated with what we consider the ego to be. It involves a lot of thinking about the past, planning the future, thinking about other people - but always in a self-referential mode. If the person is stressed and unhappy then the DMN is spending a lot of time [1](and the brain a lot of energy) on
What I think has the best potential of significantly increasing their happiness (actually the happiness of each human being) would be a transformative change in their relationship to themself. What we might call Self-Transcendence.
A couple of most promising interventions:
I think it's important that none of us actually want the brain to be spending energy on this stuff. I am aware of gratitude journaling but not of "fear journaling", "jealousy journaling", "inadequacy journaling" etc.
A single inhalation of vapor from dried toad secretion containing 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) in a naturalistic setting is related to sustained enhancement of satisfaction with life, mindfulness-related capacities, and a decrement of psychopathological symptoms
Mystical-type experiences occasioned by psilocybin mediate the attribution of personal meaning and spiritual significance 14 months later
It is rare, but does happen, that using psychedelic drugs can trigger a psychotic episode. Even though it is rare, this is a such a bad outcome that it's worth taking into consideration.
My layperson's understanding of the risks and tradeoffs right now is as follows: I think that used as a treatment for a concrete and difficult problem like PTSD, psychedelic drugs seem like immensely useful tools that should be used much more.
But for just general self-improvement or self-actualization, using psychedelic drugs feels to me like "picking up pennies in front of a steamroller" -- it will be fairly good for most people most of the time, with a huge tail risk.
I don't think it's well understood when, why, or how often this happens. I wish it were better understood, as I suspect it's specific people who are at risk and most people can use psychedelics safely. But from where I sit it seems like a -EV bet absent better information about your own brain.