Enlistment-Ending Minor Malaise

I've got eyes like a bat and my feet are flat
And my asthma's getting worse

—Phil Ochs, "Draft Dodger Rag"

An Enlistment-Ending Minor Malaise is when a character is rejected from or discharged from the military for what, in normal life, is a very minor health problem. This is typically used to explain why Awesome McCoolname, despite being strong, athletic, good at fighting, calm under pressure, and an unflinching patriot, is not (and possibly never was) in the military. These problems can kill a character's military prospects, but won't seriously interfere with his adventures.

If the setting is during a state of total warfare, this can avoid implying the character is Draft Dodging. This can be a case of Informed Flaw. A Ruptured Appendix is a medical condition with no real long term consequence, though generally won't qualify for this. Some vision problems are still disqualifying from service even if they can be corrected with the right prescription lens. Flat feet is the classic impediment to enlistment, in part because of how ridiculous it sounds.

Examples of Enlistment-Ending Minor Malaise include:

Comic Books

A variant; Barbara Gordon tried signing up for police and federal law enforcement work in Batgirl: Year One. Why was she rejected despite her stellar academics and physical ability? Because she didn't meet their minimum height requirements. While her dad could have pulled connections to get her a job, he refused. Commissioner Gordon tells his daughter bluntly that he doesn't want her on the front lines because it is dangerous, and she's safer working in a library.

Film

Inverted in Mulan. The title character argues that her father Fa Zhou has already served in the army, sustaining heart problems and a leg injury that necessitates a cane. He will die in battle if he goes to fight the Huns when the Emperor sends conscription notices. Fa Zhou asserts it will restore honor, something Mulan lost that day by failing her matchmaker exam, and he will die "doing what is right". His wife Fa Li agrees with Mulan in private, fighting with her husband and crying before they go to bed. Since Fa Zhou has no sons that can take his place, Mulan takes her father's armor and conscription notice, posing as a man to replace him in the army.

Literature

Owen Pitt of Monster Hunter International was raised to be a perfect soldier by his decorated veteran father who knew from his ow encounters with the supernatural that one of his sons was doomed to be central to the battle against the great old ones. When it came time to enlist, Owen was rejected for childhood asthma (which he no longer has) and flatfoot. Effectively free of his father's harsh training, Owen decides to become an accountant to get as far as possible from soldiery, until an encounter with his serial killer werewolf boss thrusts him into the world of professional monster hunting. Aside from being a poor runner, which is as much attributable to his massive size and heavy gear as it is his flatfoot, these health problems cause Owen little trouble.
John Abbott of Abbott in Darkness is unable to continue the family tradition of being military pilots due to being diagnosed with Marfan Syndrome, rendering him unable to endure pulling Gs.

Live-Action TV

While most of the Dad's Army cast are relegated to the Home Guard for clear cases of being too old for military service, its younger members are in the Home Guard instead of the army due to examples of this. Joe Walker is allergic to ration staple corned beef (though the loss in a BBC archive purge of its debut episode The Loneliness of the Long Distance Walker and his Black Marketeer stats give many the impression it's fake) while Frank Pike has a rare blood type.
One ongoing plot in season two of Arrested Development has Lucille accidentally enroll her youngest son Buster in the army. She spends a long time pulling strings and using her body to keep him out of combat. Turns out it was All for Nothing; a seal eats his right hand in a freak accident, forcing Buster to wear a hook.

Music

As seen in the page quote, the "narrator" of Phil Ochs' "Draft Dodger Rag" has several conditions (in addition to a host of other reasons) that allegedly disqualify him from Vietnam-era military service.

Western Animation

Looney Tunes
- In at least one WWII-vintage cartoon, Bugs Bunny was apparently rejected for military service (the sole of one foot is stamped "4F") for something so minor that it didn't prevent him from performing his usual antics.
- In another, this gets Played With. Bugs gets a draft letter mistakenly sent his way instead of to B. Bonny; he passes the health exam due to perfect eyesight and the doctor thinking he's seeing a rabbit skeleton on the X-ray due to hallucinations. When the general finds out they hired a rabbit, after Bugs blew up the military camp using a shell to hammer a photo, they say that Bugs can't work on the frontlines because he's not human. They have him testing shells in the factory instead.

Real Life

Nearly occurred with American Admiral and long distance marksmanship champion Willis Augustus "Ching" Lee, who very much needed glasses due to his childhood adventures in bomb making. Despite high marks at the naval academy, a vision test near the end would have gotten him dismissed, had the rest of the class not gathered together to help him cheat at it. He would go on to be a thoroughly excellent Admiral and his career only ended when he died seven days before the end of World War II.
Former President of the United States Donald Trump was spared participation in the Vietnam War in 1968 when his podiatrist diagnosed him with heel spurs. This painful condition that makes walking difficult appears to have resolved itself shortly after the war ended.
Stephen King mentioned in On Writing that he considered enlisting for the Vietnam War in the hopes it would inspire a book; his mother made him go to college instead because she didn't want him returning in a coffin. The biography Haunted Heart reveals that he wasn't qualified anyway due to punctured eardrums from a procedure meant to cure his ear infections as a child. (King wasn't that grateful as a child, saying the experience taught him to never trust doctors saying "This won't hurt.")