I'm 5'6 and 116lbs, I want to lose some weight, but it's not easy, what should I do?

it's been a year since I weigh 106lbs, before that I was 103lbs, I want to fit in some pretty dresses, but don't know how to shrink my body.
I'm 5'6 and 116lbs, I want to lose some weight, but it's not easy, what should I do?
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