Suggestions on how to write a speech when running for treasurer at my school?

For starters, I am in 10th grade. I tried to run for treasurer last yr, but didn't win. I'm trying to run again this yr and find out that I have to make a speech! Some qualifications may be that I was number 1 rank last year, I was in Math and Science UIL last yr, I worked as a cashier when I volunteered at the hospital over the summer, I wasn't an officer, but I was part of the council last yr, and I could mention how often I've helped some of them with math homework in the past. I could also mention that I am honest, diligent or eager to help. BUT, the problem is that I will come off too vain and people won't like that. My school is at 200+ kids at the moment, so almost everyone knows each other already. (small/new school of freshman & sopre so far) I need to make "I want to run for treasurer to help the school financially while working with my fellow officers, the student body and the staff, if I do become treasurer. Together we will make more money!" stretch out for 2 minutes somehow... :/ WHAT TO DO?!