This summary of Stoicism is very brief and only meant to give you an idea of why the Society of Stoics post what we do. Please, if you find an interest in Stoicism, do more reading on the topic.
The Stoics have four cardinal virtues: wisdom, courage, justice, and temperance. Temperance and courage are needed in men to pursue their goals. Justice is needed for the group we care about. This group grows as we age, think family, friends, neighbors, and countrymen. Wisdom is needed to be ready to react to any situation that comes up in life. It is important to note that most Stoics were teachers or politically active. The Society of Stoics wants to groom normal men into virtuous men ready to fulfil their civic duty.
Stoicism is probably the most practical schools of thought presently. The Aristotelian approach of philosophy was rather aristocratic, saying that people can only achieve happiness if they followed virtuous living and were lucky enough to be born with certain privileges in life. Where as, on the opposite side of the spectrum, the Cynics believed in total minimalistic living and thought that some of what Aristotle pursued needed to be completely avoided. The Stoics believed that virtue is the ultimate good, like the Cynics. Everything else is neither good nor bad. However, somethings may be rationally preferred by the Stoics like health, education, and wealth.