The Ryan Shazier comeback is underway ... with the Pittsburgh Steelers linebacker killin' it in the gym just 3 months after suffering a serious back injury.
Remember, Shazier required MAJOR spinal stabilization surgery back in December after suffering a severe spinal injury while playing the Bengals during Monday Night Football.
Shazier couldn't feel his legs at first -- and there was a real possibility he could've been paralyzed from the waist down.
But, Shazier vowed to defy the odds and not only walk again -- but get back to the NFL!!!
He started physical therapy last month and he's already standing on his own.
The upper body gym session on Friday is also a damn good sign.