I really want to lose weigh? please give me some advise?

So im 14 and i really want to lose weight. I wouldnt say im fat, even though i feel it. Im just so heavy! i dont know why though? So i am going to try and lose weight. The thing is i do sometimes go for a run not often but when i do i feel scared because my area is kind of rough and it makes me a bit weary so i dont know what to do. Also when i speak to my mum about it she just says im not going on a diet. I also HATE sweets? please help