The core of the philosophy seems to be this: To have a good and meaningful life, you need to overcome your insatiability. Most people, at best, spend their lives in a long pursuit of happiness. So today’s successful person writes out a list of desires, then starts chasing them down and satisfying the desires. The problem is that each desire, when satisfied, tends to be replaced by a new desire. So the person continues to chase. Yet after a lifetime of pursuit, the person ends up no more satisfied than he was at the beginning. Thus, he may end up wasting his life.
The solution, the Stoics realized, is to learn to want the things you already have, rather than wanting other things. The most interesting technique that will help you achieve this is Negative Visualization.