(CNN) -- David Shields was suffering from a bad back. And then came the attacks of September 11, 2001.
"I wanted to wrestle vitality back for myself," says author David Shields.
The two events -- the pain of his throbbing back and the ensuing "national obsession" with mortality and vulnerability, in Shields' words -- came together on a personal level for the author, who teaches English at the University of Washington.
"I was a middle-aged drudge with a vital father and an active daughter," Shields, 51, says in a phone interview. "I felt old before my time."
Believing that the best way to deal with his own anxieties was through them, he "decided to wrestle with it," he says. "I wanted to wrestle vitality back for myself."
The result was "The Thing About Life Is That One Day You'll Be Dead" (Knopf), an amalgam of memoir, sometimes envious biography of his now 97-year-old father, clinical guide to the physiology of life, and a meditation on mortality. It's a book where the literal facts of life rub up against a story about Shields' teen acne problem, which leads into a tale about boys impressing girls by diving into a lake, which abuts an anecdote about Lyndon Johnson's robust sexual appetite.
The book has sold well and has earned admiration from reviewers, even those who aren't quite sure what to make of it.
" 'Life' is something more complex than a natural history of death. It is sui generis, and that's high praise these days," wrote Alex Beam in The New York Times, though adding that the book is "larded down with faddish miscellany."
"Life's" throughline is Milton Shields, the author's father, still vigorous and sharp, a retired journalist and public relations man who literally played tennis while having a heart attack -- at age 86.
Milton Shields started out at the book's edges, but as David Shields refined the book, he felt it needed an anchor. "Only toward the end [of the writing process] did he become the center," Shields says.
He marvels at his father's vitality; he is a man, after all, who survived stepping on a commuter train's third rail, survived serious bouts with depression, hides his long-present baldness under a baseball cap and weaves "self-flattering lies" in stories he writes at his retirement community. "He's strong and he's weak and I love him and I hate him and I want him to live forever and I want him to die tomorrow," Shields writes in the book's prologue.
"My father has an emotional vulnerability, and with that comes a somewhat exhausting character," Shields chuckles. "He doesn't take the typical fatherly role. He's more his own subject." He credits his own storytelling ability to his father's willingness to create a "wonderful mythology."
But Shields is cold-eyed when it comes to mortality itself. Death may be an immovable, incontrovertible truth of life, but it remains an often taboo subject in our society, he observes.
Not that it was easy to stare death in the eye, he adds.
"I'm very drawn towards what we can't talk about," he says, noting his previous books -- including "Black Planet" and "Remote" -- have dealt with race and fame, respectively. "But I felt sometimes like I was trapped in blackness. I'd be giving [my wife and daughter] these nuggets of melancholy."
He feels rewarded by the reaction to the book -- "I just got an e-mail from a person that told me what a relief it was to talk about death" so bluntly, he says -- and that it's been good for him to get the topic off his chest.
"It feels like a relief to talk about it, rather than hide it under the American can-do spirit," he says. "I've felt oddly giddy since writing [the book]."
So much of "The Thing About Life Is That One Day You'll Be Dead," he adds, "is about eliminating all illusion."
"We're trapped on earth, and we can respond with escaping into nature, or heaven, or celebrity. ... But you're still going to die, and you'd better deal with that," he says. "I don't have anything more profound to say than 'carpe diem.' This is a pretty secular book."
And his father? Still alive, says Shields, and still determined to live forever.
"I feel compelled to pretend he's vigorous, but he seems to have declined a bit," he says. "But the best thing is that he's still full of piss and vinegar. I sent him the book, and he sent me a list of small corrections." E-mail to a friend