Mission Statement composition

Hi all,
I am a new member to the community (and a student). I have recently been given a very broad criteria (see below) and asked to compose a mission statement for the first time.

"Statement has power and meaning and provides an excellent synopsis of the key points of information needed to transmit a message. There is a very strong sense of mission in the statement"

The statement is to be addressed to the general public on the field of human movement studies which refers health/exercise promotion, sporting/competition performance enhancement and everything along those lines. As you can see the field would involve everything from very explicit exercise science research, rehab (and so on) to PDHPE education.

My understanding of a mission statement is that it should short and succinct (whether I can do it or not that's another thing), maybe anything within 1/4 or 1/3 of the page. I went on the net to look for samples but out of the ones I have looked at, they seemed to be falling in the 1/2 page category which kinda oppose to my the belief. So I am just wondering if anyone could share some of their experience/comments on it?

I also have a question about the appropriate language usage. Should I be completely subjective in writing the statement? In doing so, I might probably be inserting some of my own emotion into the piece but I don't think it is appropriate in such a context like writing a mission statement to be using emotional language. Since I will then be seen as to be putting forward a message that "professionals in my field" all share my perspective of thought which I am not capable of justifying when being questioned. I considered the impersonal approach but keeping myself distant from the field also seem to be contradicting myself as I am trying to convince readers that "I do care". Is my "concern" worth worrying about? Or have I gone off track? Should I be thinking about things like that when writing a mission statement?

Any feedback/comment would be greatly appreciated.