Need help with personal statement

My school is making us do our first drafts for personal statements but I’m struggling to actually write it

I do maths, physics and politics and am probably going to try do some sort of engineering but I don’t know what kind yet

1:how do I say “doing maths makes me better at maths which you need for engineering”without sounding stupid

2:I don’t know what to say for how politics would help with an engineering course like could you yap about it helping you to be more analytical or something?

3:I don’t know what to say for outside of studies helping me I used to be in the air cadets but left before the end of gcse (like yr10) could I talk about stuff I did in it or would it be considered out of date/irrelevant at this point