NFL star Alex Smith -- who beat the odds and returned to the field after a catastrophic leg injury in 2018 -- is retiring from football, the QB announced Monday.
36-year-old Smith gave an emotional farewell to the sport just minutes ago ... saying he's ready for a new challenge after making his improbable comeback.
"Two years ago I was stuck in a wheelchair, staring down at my mangled leg, wondering if I'd ever be able to go on a walk with my wife again, or play games with my kids in the yard," the 2020 Comeback Player of the Year said.