Beter if the MC can overcome his difficulties and try life fullest
The Millionaire Next Door by Lazlo Zalezac is an excellent read. MC has dyslexia,,,
https://storiesonline.net/s/54088/the-millionaire-next-door
An older protagonist with leg injuries/amputee was a common theme in Mystery Writer's stories - good tales but lacking a good editor.
AJ
RLfj's MC is a normal physically fit kid who goes to Iraq. After a last stand of the 'fire mission on my position' type he leaves the military with a bad case of PTSD. With the love of his fiance and friendship of his men he recovers and leads a very successful life: https://storiesonline.net/s/11339/the-grim-reaper-romantic-story
Harry Carton has two.
MC in 95 has a stroke type brain injury from birth. Still grows up to have a wife and family.
https://storiesonline.net/s/76175/95
MC is a double amputee vet who keeps on trucking.
https://storiesonline.net/s/75643/its-not-what-you-think
Reluctant Sir has a couple where the MC suffers severe child abuse with the resulting mental damage, but grows up to be functional human beings.
Echo is a do-over where he dies and wakes up back in his childhood with his psychotic stepfather and brother:
https://storiesonline.net/s/18102/echo
Dark Days & its sequel has a child who's parents and sister have been murdered, being rescued just before he is murdered. Obviously he is a mental wreck as a result.
Good people help him recover and he sets out to be a better man.
https://storiesonline.net/s/18210/dark-days-darkest-before
Another story by Reluctant Sir is Unending.
MC is severely injured in a terrorist attack. Story includes his recovery and reconnecting with family.
https://storiesonline.net/s/14757:223482/chapter-1-unending
Joe J's Honky Tonk Hero
"A coming of age story with a twist. Addle-brained Tommy works down at the feed store, stacking Purina and sweeping the floor. A Vietcong rocket scrambled his brains so thoroughly that was all he was capable of... or was it?"
An most excellent and high scored story. I re-read every once in a while.
Judgements by Moghal - MC has autism spectrum (can't remember exact diagnosis)
The Cripple by OldSarge - two major characters with leg injuries
Lazlo Zalezac's Jade Force stories had a major character who was in a wheelchair, and still a commando.
Amateurs by Frostfyre - Triple amputee, missing one eye, with severe PTSD... takes down terrorists in a hurry.
There's also Lazlo's Hunter. Marine has a crippled hand from combat in Iraq and goes on to hunt terrorists for the CIA. https://storiesonline.net/s/52923/hunter
Charles "Chuck" Johnson appears in several of Dual Writer's 'Florida Friends' stories starting with 'Job Hunt' is a medically retired from the Marine Special Forces after losing his right leg just below the knee in Iraq.
Second Chance by Number 7 - DoOver, MC keeps ending up in bodies that have been damaged, the first with multiple aneurisms.
IIRC 2 Flags did a Damsels in Distress series with a MC who'd been paralyzed. Actually, a few authors used that universe to 'heal' MCs who'd been damaged somehow.