Defining a core mission involves introspection and understanding the underlying motivations behind starting the venture. Here are some steps to help define it: 1. Identify your values: What principles and beliefs are most important to you as an entrepreneur? 2. Understand your impact: How do you want your business to impact your customers, community, and industry? 3. Keep it concise: A good mission statement is brief and to the point, typically one or two sentences. 4. Make it actionable: The mission should inspire action and guide decision-making.