My arms gets bigger/fatter as I observe I frequently carry my child who’s 10kg now. Any exercise to get it back to a slimmer shape?

I usually do it at the end of the day right before bedtime. Its not too strenuous so dont worry about not being able to sleep after that. Back when I was working shifts, I used to do it in the backroom of my duty office when there was no one around haha. Since its only a few seconds/minutes a day it's actually very easy to manage :) good luck!