Another post reminded me of something I thought I'd share.
Some years ago, a friend was picking me up after I dropped off my car at the shop. He asked someone there where he might find me and the guy said something along the lines of "is he that big tall fella?" That really struck me because I'd always thought of myself as a skinny little kid. In fact I'm 6'2" tall, 210 lbs (at the time I was a bit lighter!).
A couple of years ago my mother sent me a package of old childhood stuff that included my school health records, so I made a chart showing my height and weight over time. Very illuminating! Seeing my body size plotted out over time helped me understand that I really was a little kid then, and I'm not now.