I have some stories to relate from my church. Like many, the congregation is mostly older folks, so they're not immune to health scares. But how they've handled them is night and day compared to Jack's retardation.
One woman broke her hip after falling off a bike (which, by her own admission, had been a stupid idea). She had to do physical therapy, but instead of complaining about it and not going, she struggled through it like they told her. Within a few months, she went from needing a walker to being back on her feet like normal. No more bike riding for her, though.
Another man recently had a stroke after a couple of circulation issues he'd been having (ironically he was supposed to go to a followup on that later that week). It didn't affect motor skills, but his speech was thrown completely out of whack, struggling to find words and convey the thoughts he was having, often limited to barely getting a single word out. But he's been in therapy since then, and has even started coming back to church already. He's noticeably a bit slower than before, but his personality is unchanged and he can get full sentences out, and hopefully he'll regain most of his function.
Most recently, our organist had to be taken to the hospital where it was found she has COPD and stage 1 congestive heart failure (long time smoking and later vaping). After the hospital stay, she was moved to rehab which is where she's at now. She wants to come back and play as soon as she's able, and I have no doubt she's going to work hard at her therapy to try and get to that point if she can.
It's good to have faith and pray for recovery, but just sitting around and waiting for God to magic your illness away, especially when you can do something about it, is peak stupidity. Jack could have done literally anything to avoid the condition he's in now, but he refused to give up his gluttony or work to regain the function he'd already lost, and thus he deserves his infirmity.