A pancreatic disease. Since you'd met him, you'd been the first (and only) person to have discovered his disease. You were the only one who knew he was going to die within the next year.
Yet, he seemed so...nonchalant about his impending death. He seemed oblivious of it. As if the gravity of his disease never kicked in. Was he really content with simply dying? Surely there were things he wanted to do before he died, like a bucket list or something..
Your curiosity on the subject lead to you asking him straight - no sugarcoating.
"Hm? Well, you're not ticking off everything on your list right now, are you? For all you know, you could get hit by a truck tomorrow." He smiled, his reply being a lot more light hearted than you were expecting. "The way I'm going through life is no different than you are."