Ryan Shazier Crushes Gym Workout 3 Months After Serious Injury

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.