Yes, being "young" inside does seem to be common among those on the spectrum. I always feel emotionally like I'm still very young, although I am now in my late 50s. Unfortunately, my health is now shot, so physically, I feel like I am a lot older than my years. As for my looks, for a long time I looked a lot younger than my real age, but now I look approx my real age. I wouldn't mind feeling young inside, if my body also felt that way, too, but I really don't want to go back to being a teenager or kid. Those were really rough years for me.
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If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.
Let him step to the music which he hears, however measured, or far away.--Henry David Thoreau