The Washington Redskins quarterback needed the ligaments in his knee reconstructed after aggravating an injury during the playoffs.
The offensive rookie of the year told reporters: "The knee is good. I'm three weeks out, so to be able to walk around and do all this stuff, I'm pretty far ahead.
"I think you will see a different version of me. I vowed to my teammates and to myself after my first injury [sustained in college in 2009] that I'd come back a better player, and that's what I plan to do after this one as well.
"You won't see the same Robert Griffin, you'll see a better Robert Griffin."
The 22-year-old led the Redskins to the NFC East title, passing for 3,200 yards including 20 touchdowns.