What are they looking for in a PGCE personal statement?

[prospectiveteacher]

I'm a bit late in applying, but I am hoping to be accepted to start a PGCE this September but I am really struggling to write my personal statement. I've got some work experience in a secondary school already under my belt, with another 5+ days booked in a different school in the next month or so. I'd love to be a teacher (but I'm under no illusion that it will be tough and an extremely challenging job) and I love my subject (History) and really think that I'd be able to inject some of this love into my own teaching practice. I've got teenagers of my own so I am pretty familiar with the secondary school system and the highs and lows of just being a teenager these days. Once I get going on it I think I'll be able to write something meaningful but I just can't get started at all. Anybody able to give me some pointers/ideas that will at least get me to interview?