How to be confident shirtless?

I'm going on holiday to a place with a pool in a few days, so not enough to change my body, but I'm very insecure. How can I mentally become confident to go shirtless? I'm actually almost considering just not going in the pool at all, but I like the pool and I want to get over my insecurity.

The problem is not so much the being shirtless in front of strangers as it is being shirtless in front of my friends and family; I mean I am also insecure about being shirtless in front of strangers, but the thing is I'm not normally shirtless around my friends or family at all, and I feel like they would almost think less of me if they found out how my body is much less attractive than my face. I know that's a weird thought.

I'm insecure because I'm skinny and pale, although I do have a slight muffin top which I'm also really insecure about. I also have pretty bad acne scarring on my back and shoulders. I intend to change all of this, but it takes a log time - we leave in 3 days haha.
How to be confident shirtless?
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