Imagine a world where no-one aged and we all stayed the same. How would that work? You pick an age you want to stay at?
The beauty of living long enough to age is that you get to be every kind of person. The baby, the toddler, the child, the teenager, the young person, the parent perhaps, the middle aged person, the older person, the grandparent perhaps, and the elderly person ... with a long, interesting and eventful life behind you hopefully.
The alternative to that is that you die during one of those stages. You die as a child or a young adult or in middle age .... because from the moment you are born the only thing that can stop you ageing is death.
To rail against it is such a terrible and pointless waste of energy. It is as inevitable as the world turning.
Instead why not celebrate it? You've made another year, another decade, you've done more things, been to more places, met more people, had more experiences.
There is nothing to stop you being your best self at any age. At sixty you are never going to look like you did when you were thirty, but there's nothing to stop you being a fabulous sixty year old. Keep yourself fit, eat well, take care of the body you live in and cherish every day.
One of the best benefits of ageing I have found is that with every passing year you give less shits. I don't mean literally 
but rather you don't give a shit about the things that used to bother you. And post-menopausally (as I am!), you really don't give a shit. It's so liberating, and even exhilarating, not to care what people think of you, not to be crippled with self-doubt and insecurities. You say what you think and you mean what you say .... and it's bloody marvellous.
I'm so much more secure and happy in myself than I was when I was younger and lots of older people will tell you the same. And I was someone who cried when I turned 30!