Craving cookies, need discipline?

How do I impove my discipline and self control for myself? I'm 15 years old, im a track runner. I'm not fat just have big goals, like wanting to get ride of the extra chub in my belly caused by sweets. I get so mad at myself for eating them. I've tried making healthy cookies and celebrate Friday with pizza, but I once I start eating junk Ican't stop!
Craving cookies, need discipline?
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