People need a compelling reason to follow your lead.
This is why you need to create and communicate an inspiring vision of the future. Your vision sets out your team or organization's purpose as to why you all get up in the morning to do what you do. You develop this partly by understanding the values of the people you lead, partly by understanding the capabilities and resources of your organization, and partly by conducting an intelligent analysis of your environment, and selecting the best way forward within it.
This is the subject of unit strategy; developing a coherent strategy takes a lot of hard work and careful thought.
If you're developing a vision for your organization, use Mullins' Seven Domains Model to analyze your environment. Then, use tools such as Lafley and Martin's Five-Step Strategy Model to develop your strategy. This is usually then expressed in a business plan, and summarized in a mission statement. If you're developing a vision for your team, start with the school’s (company’s) mission and vision, and explore the ways in which your team can contribute directly to it.