I suspect that most people don't actually fear aging, they fear the closing off of possibilities. Which unless you have illusions of athletic fame or have based your entire self worth on being seen as fuckable by the 18-24 age bracket, is pretty much entirely artificial external pressure you should be allowed to say "fuck that" to.
Much of the rest, I suspect, has to do with the fear of developing disabilities, which really says so much about how horrifically capitalist societies treat the disabled. That something pretty much everyone is going to experience some day if they're lucky is treated with horror and revulsion rather than as something inevitable to be accommodated.













