You should have included a description for people who dont wanna watch a video..

Here are the four ways you'll need to revive someone to unlock the achievement.

1 - Normal revive

Simply revive someone to get this (Get a friend to down himself, being crushed by a Giant, getting hit by a Zombie or cooking a Grenade will all work.)

2 - Quick Revive

Revive someone while you have the Quick Revive perk on you.

3 - Maxis Drone

There are three pieces to build this, once built, get a friend to go down, and then hit down on your D-pad to activate the Maxis Drone once you've picked it up, it will then revive your friend if you are close enough. (This will also shoot zombies so make sure to be away from a crawler if you don't want the next round to begin)

4 - Ultimate Staff Revive

Build an ultimate staff, then hit left on the D-pad to select a healing rod out, shoot it at your downed teammate.

Saving the Day... All Day is a zombie-related gameplay achievement/trophy featured in Origins for Call of Duty: Black Ops II. This achievement/trophy requires the player to revive another player four different ways in one game. There are five ways to revive a downed teammate to complete this achievement: the standard revive, a revive with Quick Revive, a revive while in Zombie Blood, using the secondary use when wielding any Ultimate Staff, and using the Maxis Drone.