Whenever I catch myself talking negatively to my body, I use this quick personal mantra as a reminder to bring myself back to peace:
It is not for me to decide whether my body is good enough or not.
My body is a divine gift, a temporary home for my soul, and it's on loan to me for the duration of my life.
It was designed perfectly for the specific purposes I am here to fulfill (whether I know what those are or not).
There is a reason I look exactly the way I look, even if I don't always like that.
Once I've accepted that I don't call the shots on the raw materials, I look at the part that IS within my control, and that's how I treat my body. Usually the times I'm not so happy with my appearance is when I haven't been doing the self-care thing too well.
So, beating and bashing myself is not going to help me. I can't come up with the next right action if I'm in a head-place of negativity and self-loathing. My first job is to find my way back to feeling good. I may not be feeling good about myself at first, but if I can get to hopeful or positive or capable at least, I know I'm en route.