How do I gain self confidence??

Here’s me. Girls at my school argue that I’m perfect, that I’m pretty, smart, funny, athletic, etc. What I don’t tell them, is that I see none of this in myself. I have struggled throughout the years to truly love myself and have pure and utter confidence. Whenever I see another girl I think is pretty, I will immediately snap to the conclusion that I should be like her or that I want her life even though I know that is so wrong. Have you guys had any similar confidence issues before? How did you guys gain self-confidence and love yourselves for who you are?