Rule #1: Make life as hard as possible for your protagonist.
You have to throw it all at the protagonist. No matter how much shit they are in, you add more.
Let me show you an example:
The Attack: The story starts with your protagonist having a violent stomach pain sending them to the emergency room. Where they find out they have to have surgery on their stomach.
You might consider stopping there but this is not interesting enough. Let’s take it to the next level.
Swelling arm: They place an IV in his arm but as the nurse begins to walk away his forearm starts to swell up like the middle of balloon being squeezed; the IV is not in the vein.
Swollen prostate: Before they even get into the operating theater, you need to throw something in from left field. He has a reaction to the pain medication which causes their prostate to swell.
Stabbing pain: To the screams of the protagonist, an inexperienced nurse tries and fails to insert the catheter three times before she is told to use the numbing cream.
Blood transfusion: Finally, your protagonist has the operation only to wake up unable to move his massively bruised arm follow a blood transfusion.
Now we are starting to warm up but we still need to crank it up some more.
Hallucinations: Once more the pain medication, the second lot, causes problems leading him in to frightening nightmares and hallucinations about his children.
Pain and more pain: Unable to use liquid pain killers he is give oral pain medications, but he begins to throw up from the stomach operation as nothing is passing through. The pain gets worse and worse.
Losing Blood: Without warning, his blood starts to pour out of him, liters of blood, the lost blood from the operation.
We can add a third party.
Homeless guy moves in: With no available private rooms the protagonist has been placed on a ward and a homeless man is given the bed next to him. The man smells like a sewer and has a hacking, mucus laced cough.
Security: The man’s visitors arrive drunk or high and clash with the security, even when there are sober they smell and take the food off over patient’s trays.
Even after things seem to improve really kick it up.
Bursting stitches: Eventually, he is sent home but that night he violently throws up and the stitches in his stomach burst open in an explosion of puss and blood, leaving a deep hole in his belly and our protagonist back in hospital.
Never ending weight loss: It is eleven days before the protagonist stops throwing up but then the diarrhea starts, for five more weeks.
Now you have a protagonist in peril.
You might think this is too much, but I can tell you this is actually not fiction—the picture is me doing quick selfie on the way back to hospital—and if real life can be this hard then fiction should match it at the very least.
Rule #1: Make your protagonist’s life a living nightmare.
Finally, I need to make as special call out to the nurses at St. Paul's hospital - Ladies and gentlemen, you are amazing and I can not thank you enough! THANK YOU!