It's a tough one: zombies! Here's a link to other contributions.
Oh, he knew about zombies all right – sitting slouched over his desk he'd read every book and online source and viewed all the movies, but took special interest in one recurring theme. The erratic behaviour of humans in a collapsing society was as much a source of personal danger as attacks by the living dead.
He stopped eating junk, learned how to secure a house against invasion and to defend himself, mastered techniques of survival in haunts where all the trappings of civilisation were absent, developing taut lean muscles, mental endurance and a newly generated maturity.
With the transmutation far advanced and zombie books no longer the focus of his interest, he made a neat pile of them on his desk.
"At last you've come to your senses," his father said, peering with profound distaste at the books destined for disposal, "that zombie stuff was such a ridiculous waste of time."