Start with what you know. Your face. Your neck. Your shoulders, and all that rests below.
The freckles are getting bigger. You refuse to call them "spots." But you know this is age, reminding you that you are part of the human race. You are not exempt from the mottling, the grays, the aches, the droop, the sag, the parchment skin of your grandmothers. You loved their skin, can feel the thin, dry, papery touch of it under your plump child's hand. Skin was not then something to fear.
Fear is not the word, not exactly, for any of it, even now. You mostly wonder at the changes the way you would wonder at a funny color in the sky, some peculiar green-grey-rose in the distance, just before a thunderstorm. You scold what's different now, sometimes, when you see in photos that you are not immune to this comic, endless march to yet another, and then another, and then another version of yourself.
The trick is taking a few steps back from the mirror. No, still more. There. Better.
Those indifferent to you see you from this distance, or not at all.
Those who dislike you—despise you, even—will hold tight to their Sherlock Holmes magnifying glasses and their megaphones. Let them look, let them sing of your faults, in numbered order. This is all they have.
Those who love you will remember the feel of your skin under their hands, the way you remember your grandmothers' skin. They will remember your cold feet tucked under their warm legs. They will remember your hand tugging theirs to keep them close as you walk. They will remember your fingers combing their tangled hair. There is no way this is not beautiful. This will always be beautiful, even after you are gone.
Those who desire you will remember the way your skin moved under their hands—and either wish to remember, or wish to forget.