I personally do not feel safe on a 40 year old airplane that takes off and lands 10 times a day, or more.
That old plane gets regular care, inspection, and maintenance, unlike many of us. The air frame may be forty years old, but many, if not most of the moving parts are much younger.
I have flown regularly on charter flights to the Channel Islands (U.S.) since 1982 on a plane that was old then. It is probably pushing fifty years. It gets very good care, and I know the pilots are thoughtful and cautious.
With every passing year, I appreciate old things more and more.