It's not necessary to dream big or to grow fast. Be clear about your passion and ___ ___ it. (stick)

根据句意，前半句“Be clear about your passion”表明要明确自己的热情，后半句需填入“stick to it”以指代“your passion”。此处“it”为代词，避免重复。“stick to”表“坚持”，与“Be clear”构成并列结构。完整句子为：“Be clear about your passion and stick to it.” 答案：stick to it