Contentment results in happiness. (PYS II.42)
Pema Chodron said "When we have nothing, we have nothing to lose." An enlightened mind is one that knows santosha or contentment. It means that things don't have to go one way or another, our desires don't need to be fulfilled, our situations don't need to change in order for us to feel settled in. The enlightened mind knows that the constant shifting of the idea of what we need to do more or have more is a futile activity. The standard of "if" in "if this happens, I will be happy" will continuously change. It is like the shoreline by the beach. We can attempt to write our conditions for happiness there, but eventually and inevitably, they will be washed away. Contentment is to see that those conditions need not arise for us to be happy, that even during those times when we feel sad or lonely, we can be fine. We do not need to hanker for something external. There is nothing to be "solved" or to be "fixed" when it comes to the natural ebb and flow of our emotions or states of mind.
To know contentment is to acquire the skill of just being. Not doing, and certainly not having, but just being. To be here, with all that you feel, all that you have in you, all that you carry in you and with you and be okay with that is contentment. To see things for what they are, without desiring for the situation to be different, without anxiety for the future or regrets of the past is the reality of the enlightened mind.