Which of the following is NOT one of the three key stoic concepts?

The answer is identified accurately, as the statement that life is only about finding happiness does not align with the core principles of Stoicism. Stoicism emphasizes the importance of virtue, wisdom, and self-control over the pursuit of happiness as an end goal. Instead, Stoics believe that the path to true contentment relies on living a life of virtue and understanding what is within one’s control versus what is not.

Control what you can and accept what you can't captures the essence of Stoic practice in managing emotions and reactions to external events, promoting a realistic approach to life’s challenges. The idea that virtue is the highest good is central to Stoic philosophy, which posits that moral integrity and character are what truly lead to a fulfilled life. Furthermore, the view that emotions are responses to judgements rather than factual truths reflects Stoicism's focus on rational thought, emphasizing that our interpretations dictate our feelings, rather than the situations themselves. Thus, the statement about happiness does not represent a Stoic belief and is fundamentally at odds with the philosophy's core tenets.