Chris Johnson Trained with Bullet In Shoulder ... Says Jay Glazer

AZ Cardinals running back Chris Johnson was so determined to revive his NFL career -- he hit the gym like a maniac this off-season ... even with a bullet still lodged in his shoulder.

We spoke with Jay Glazer -- who trained CJ2K's at his Unbreakable Performance Center in L.A. over the summer ... and says he was SHOCKED when Johnson approached him to work out after being hit in a drive-by shooting back in March.

As we previously reported, Johnson was struck in the arm in the attack -- and the driver of the car was killed.

But even with the injury, Glazer says Johnson refused to give up -- pushing himself harder than most professional athletes who walk through the door.