Letter of Application Help (& personal statement)

Hi, I'm applying to be a House Leader at sixth form, and have to write a letter of application to my head of house, detailing why I want to be a House Leader, and why I would be good at it.

I have mostly got it sorted, and am basing it (loosely) on a personal statement sort of format, but I'm struggling to think of an example of when I have shown determination and/or perseverance..? Can anyone think of a generic yet not-so-generic-it's-obvious example? Thank you in advance!

(Also I'm sorry about the terrible layout of this, my enter button won't let me do a new paragraph)