The phrase 'having oneself' means to maintain composure and control over one's emotions or behavior in a given situation. Synonyms for this include 'keeping a level head', 'maintaining one's cool', 'remaining composed' and 'keeping one's head'. These phrases imply the need to stay calm and composed in stressful situations or when faced with challenges. Another way to express this idea is 'exercising self-control', which stresses the importance of being aware of one's emotions and thoughts and regulating them accordingly. 'Being in control' or 'staying in charge' can also be used to express the idea of having oneself and taking charge of a situation. The ability to have oneself is a valuable skill in both personal and professional settings.