Royal Navy fitness test, training for it?

[JDYgamer]

I need to get fit for joining the Navy, but every time I get all motivated it only lasts a couple days and then I get right of it. It's definitely what I want to do, but my main problem is that I get all excited, go in at the deep end and when I'm not doing very well I just lose my temper and pack it in. Up until like a few weeks ago I had a tread mill and now I dont. I think this is going to make it so much harder. I'm trying to come up with a routine to start running the streets, but as I'm writing it I know its too hard, but can't seem to tone it down. Can someone please help me get a little fitter by maybe posting a routine they have used in the past? Or one that I could possibly use?

Oh. I have to run 1.5 miles (2.4km) in 12 minutes at the end of it.

Thanks guys.