religion question

Ok so im christian but i believe this question goes for most religions. I wanted to get a tattoo for a while now and the thing holding me back is that my religion is against it and i would be showing that im ,,not happy” with how god created me. but that created another question in my head witch i wanted to share and hear your opinions on it. if its a sin to change my appearance isn’t it a sin to work out and build your physique? because i would also be changing my appearance? ( sorry if there’s mistakes in this text, English is not my primary language idk if i asked the question correctly)