Also, consider whether they actually want to. At some point, some people have had enough of life and don't want anymore, even if they're healthy (I'm not 40 yet

Also, consider whether they actually want to. At some point, some people have had enough of life and don't want anymore, even if they're healthy (I'm not 40 yet and start to feel it ;)) But as mentioned before, get some kids, sure they will make YOUR life comparatively miserable, but your parents will love it ^_^