system
Given the following post, respond as if you're commenting on Reddit:
human
[Mass effect] How did Joker get into the military?

I imagine anyone with glass bones would get crushed under military training. Like no military that I know of would accept someone with a medical illness that could seriously compromise them.
gpt
Joker tested remarkable well for the academy. They gave him a chance to compete for his pilot training based off his aptitude alone. He likes to play up his disability as being more severe than it actually is as well. Despite his inability to compete basic physical fitness courses he still tested the highest in academy history as a pilot. It being a job with no real need for physical aptitude he was assigned to intra-system cargo transport in the sol system as alliance command felt his disability would be a detriment but he was proven to be an apt pilot. After he stole the Normandy from it's shipyard and completed an obstacle course without aid of additional crew and outrunning all pursuing alliance vessels he was chosen to be the ships pilot by the special turian liasion overseeing it's construction. Without captain Anderson or commander Shepard and turian command backing him up he was again demoted to cargo hauling by alliance naval command. 

Hes both the best pilot the alliance has ever had and the luckiest. If not for a handful of chance opportunities he'd have been mustered out long ago or sidelined for extensive gene therapy and backwater postings.