Great, I told you more but my note wasn't published.

Summarized, Stoicism defends that there is very little in our life that we have power on. We have power over our thoughts, opinions and actions. Over the rest of existance (our health, our fame, our loved ones) not really - that's under the purview of Logos/Nature/God.

Moral good can only be found where we have power on, as otherwise being good or bad would be random or arbitrary, and as such wouldn't be moral good or bad.

A happy life (eudaimonia) is a life lived in the pursuit of virtue, which is objectively derived from our nature as rational beings. The four stoic virtues are Courage, Temperance, Wisdom and Justice. Other material stuff we can prefer or disprefer, but they are fundamentally (moral) indifferents. For example, the death of a loved one isn't good or bad, it simply is. Good or bad is how we might react to it — wallowing in our own dispair would be bad, accepting it as part of life and continuing on would be good.

This is all supported by a detailed system of physics and logic, which can get pretty deep. Also, traditionally Stoicism was (and is) a profoundly spiritual philosophy, which is something many times set aside nowadays.