Its honestly just how you take care of yourself. I when I went home on leave last Christmas, my eldest's former best friend fell head first into a pile of meth and you'd never guess that she wasn't even 20 with how old and worn down she looks. I've never wanted to full combo someone else's parents so badly til I saw the bright eyed girl who I took to watch the Spurs play basketball with my kids now look like she was pushing 50 missing a number of her teeth.