What is it that first motivates your team? It is knowing why they are here. And that's what your mission and vision get them. But, how do you set your project team's vision and mission? I will tell you.
This is a Project Management channel, so while I could come up with something, it may not be realistic. I am happy to try to help, so please respond with some more context, so I can tailor the answer. Different contexts will have different examples.
Well, Meta (Facebook parent company) has a vision statement: 'to bring the metaverse to life and help people connect, find communities and grow businesses'. Google’s vision statement is equally bold: 'to provide access to the world’s information in one click'.