My first guitar, a Silvertone Classical from 1970, still have it:
That would make it 49 years old.
My first good guitar, a Kalamazoo-built '74 Gibson Small Script Les Paul Standard I bought used in 1977 and still have. Pic is from 1978:
It's a '50s revival band. Note lipstick on cheek.
And today:
45 years old
Bob