Lasting happiness? There's always going to be downs as well as ups in life. Stoicism will teach you how to handle the pitfalls in life without dwelling on them and helping you to get on in life. Buddhism will help you to understand that life is full of sorrow but that the journey is it's own reward and that joy can be found anywhere.

A perpetual state of satisfaction can be reached that's liberally peppered with happiness. Happiness is not an end goal. It's the after affect of a effortful life that invites playfulness and new experiences.

The key word here is effort. Happiness should not be the main goal. Living your values. Finding a process and journey that meets your values and challenges you slightly will bring satisfaction.

Be carful of self help books and systems. Many are designed to put you on a perpetual wheel of needing more and more books to buy and classes to take. They are money generators that will tell you they offer the golden cure. And if you didn't succeed with the system in a few months then here's part two you can buy.

I do like THE HAPPINESS LAB podcast as a starting point. There's a free Yale course too. The teaching there can get you to examine some stuff.

Be kinder to yourself but do put some challenges in your way. Happiness is not about having a placid life.