20 y.o.'s...By that you're probably referring to young adults/teenagers category, and no most don't fear death, because oftentimes it's the furthest thing from their minds. You know the old stereotype "those types act like they're invincible". Most stereotypes are around for a reason: they're self-perpetuated. But I digress.
I think that the author of this topic is a little misguided. Acceptance of mortality is very healthy, so long as it doesn't go as far as causing indifference to one's own life("oh well, who cares? I'm dying anyway."). Is that person really believing that we SHOULD be afraid of facing our own demise? And what's the reason for reinstating this fear? I don't see it doing any good to anyone, least of all things life extention (and besides, I'm much more a "quality over quantity" type anyway *lol*. What good are extra years if they're wasted on fear?). I've seen (and read about) more than my share of people not only dying despite their fear of it, but dying in the very manner their worst nightmares, phobias and imaginings illustrated. For example, a claustrophobe's body recovered from being locked in a dark, small enclosed area. A person afraid of heights falling to their death. ONE example in particular really stood out for me...you want to talk about "power of the mind"? One guy worked on freight trains and his biggest terrifying fear were the refrigerated freight cars. His fear of being locked inside and freezing to death was so strong, it bordered irrational. Everyone that knew him knew about his fear. Well, one day, it happened. He got locked inside one of the refrigerated cars as the train was leaving for an overnight trip. His body was found at the destination. Autopsy indicated that he died of freezing to death...But HERE'S the TWIST: the refrigeration WASN'T TURNED ON! The power of his mind combined with his fear and ALL IT'S STRENGTH, when misused (as in this case), worked against him and took his life. If he hadn't have been gripped by the terror of dying (and the manner of which he'd die), he would've just missed a day of work *lol*.
Maybe the route to take is the view that mortality SHOULD be accepted...but seen as an option of whether or not to participate *lol*. Sticking your fingers in your ears and going "la-la-la" over the facts is about as blockheaded as living in fear over it.