If you want to see what you will look like when you're older, stand in a spot and jump up and down repeatedly. Take photos (or pause a video recording) right at the moment after the lowest part of your jump. The upward acceleration will make your skin sag the way gravity will as your collagen weakens over decades.
But then again, by the time you're older you might look younger than you do now, e.g. "Ageing changes our genes – epigenetic atlas gives clearest picture yet (nature.com)" https://news.ycombinator.com/item?id=45095532 (from the other day, no comments yet)
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