Age is just a mindset, in fact, it is a mental construct.
Now is the only real moment of our lives and always will be. All the time, another mental construct, that has come before no longer exists, it is just a memory in our mind.
Just live each moment and then your age is no longer dominating your self-image, your story of the past no longer influences you now and there is no need to worry about how many years you might have left and so on. You do not have to then think about acting an age!
Life, even on your death bed will always be now not what age you are on your birthday.
The universe works with you once you let go and accept what is.
Once you allow the flow of things to unfold in the moment, and remove the negativity of fighting the reality of what has already happened, then things come together without the need to keep trying to make it happen.
It is our resistance to what already is that causes the negative thought, the negative vibrations, the negative emotions and we become those thoughts, reactions and emotions. Then we wonder why things have not happened or turned out how you imagined.
Stop imagining a future, stop fighting what is and allow the flow of this moment. Let the universe work with you.
Of course, your mind will tell you this is all nonsense, but worth a try at least.