I learned this lesson from my grandfather when I was about 6 years old. We were sitting in his house in Ocala, and Papa was telling me that he and "the boys" had gone to a baseball game the night before.
“You said ‘boys’! You're a man! Why do you say ‘boys” when you’re as old as you are?” He was in his early sixties, with gray in his thinning hair.
His response was: “You never get any older. Your body gets older, but you stay just the same as you always were. Inside, I’m no older now than I was when I was your age.”
That may be the most important thing I ever heard from an adult. It has stayed with me all my life. I feel now as much as ever that it is true.
Only the body ages. The "I" is part of the eternal Now, which has no beginning or end and therefore no progression toward an end. You are the passenger in the chariot of the body described in the Vedic writings of ancient India. You are not the chariot, although you are the "enjoyer" of the chariot. You are the "ghost" in the expression, "the ghost in the machine". You are that Consciousness which watches the sights that your physical eyes bring you. It's analogous to watching television: You are not the television set.
A convenient word for this eternal Self is the "Soul". Although I don't subscribe to any organized religion, I sense that my Self, my consciousness, is immortal and not a mere product of the body. I also sense that the Person who woke up in my body this morning is the same as the Person who woke up in it when it was seven years old.
Now this body has been in use for 77 years, and I don't like what is happening to it compared to its newer condition, but at least I know that "I" am no older. If one truly feels this, some of the grotesque features of aging can become a bit humorous -- like sailing along in a little sailboat in a strong wind with parts falling off.
I highly recommend that you read "The Power of Now", by Eckhart Tolle, which eloquently expresses the eternal Now.