I used to work with a lady that nearly died after stepping off a boat.
The lady in question lived on a canal boat, and on one occasion when she stepped off the boat onto the grass at the side of the canal, she felt a sharp pain in her foot.
So she assumed that she'd twisted her ankle and thought nothing of it.
As it turned out, there had been some kind of freak muscle compression when she put her weight on the foot that caused a massive deep vein thrombosis to form at the base of her leg. As sometimes happens with DVT, when it moved and nearly killed her.
I also knew someone who suffered 1st degree burns from flu. (She fainted due to having a fever and fell into a seated position with her back resting up against a radiator on full blast. When she was found several hours later by her husband, her back had literally been melted onto the radiator)