NFL's Josh Gordon -- I'm Busting My Ass ... for NFL Return

Josh Gordon has been hittin' the weights ... hard ... killing himself to get ready for his NFL comeback in 2016 -- and judging by the footage of his workouts, dude looks ready to go.

The Cleveland Browns wide receiver was suspended for the 2015 season for violating the substance abuse rules -- but he's vowed to make a comeback and it looks like he's taking things seriously.

Gordon's agent Drew Rosenhaus previously told us the 24-year-old is keeping his nose clean and "doing all the things he has to do to get ready. We fully anticipate him being back for the 2016 season."