This can be boosted very early on in the game. First things first, you'll need someone on your friends list who is playing the game and willing to join your game or you joining theirs. If you don't have anybody, please go HERE.
Once you've got a partner and are in a game, you'll now need to find an enemy. Going into "Fight for Your Life" mode is kind of like "Last Stand" in Call of Duty. When your health is depleted to 0, you'll die but go into "Fight for Your Life". Being in this mode, you can only crawl at a slow pace but you can still shoot your weapons. If you manage to kill an enemy before the new health bar is depleted, you'll be brought back to life and get your "Second Wind". But for this achievement, you don't want to do that.
Once you've found an enemy, either you or your partner stand there and let it kill you. Now have either yourself or your teammate walk up to each other and you'll then be prompted to press and hold to revive. Doing so will bring them back to life (when the green bar is full) without them having to shoot and kill someone and the achievement will unlock. Just make sure you revive them before their health bar runs out, otherwise they'll die indefinitely and respawn away from the fight.
*This can also be done with a second silver XBL account. Simply log them in, and then continue to follow the description above.