There are diseases that cause all manner of misery. Some conditions result in the loss of body parts. And you will most likely live through the ordeal.
When it comes to monsters, humanity has them in abundance. A beast does not delight in murder. However, a human being can rejoice in utter wickedness.
Pain comes in many forms. Whether by accident or intent, serious damage can be inflicted. And life becomes a living hell.
Appreciate what you have while you still have it. No one knows when their luck will run out. That which was given can so easily be taken.
To live in fear is among the most terrible of fates. We all know about what could happen, but it is pointless to dwell on it. Enjoy the unreal, and then get out and live before it is too late.