Nothing I ever found undoes the root of our misery better than Vipassana.
SN Goenke based retreats are by far the best method, and I always recommend them to anyone. Sure, it is not easy and it is a lot of hard work, but our misery occurs because our life has been spent craving good things and feeling repulsed by bad things and that builds up over time into the inner existence of misery, which we then continue to feed with our endless reactions. There is no easy cure because of what we fundamentally are, and because of what being alive is all about — we are here to experience life.
Anyone miserable actually needs to stop talking about it, and go find their nearest Vipassana centre, then go on a 10 day retreat, it is donation based so there is no reason to claim poverty and avoid doing it that way. Then come back and talk about their misery. Because there is nothing like misery to get people talking about their problems endlessly.
I think the best solution when someone wants to tell you how miserable their life is, is to put your hand over their mouth. Stop them speaking about it. Being miserable is addictive. Misery loves company, right?
So, go do Vipassana, and then you will have earned the right to discuss being miserable because you will understand why you are miserable and also, importantly, you will have been given a tool to deal with it. Until you have at least put some effort in to addressing the problem, shut up and stop moaning about it !
Vipassana Centers exits around the world, here is a link to find the nearest one to you –