Successfully complete Training Mission 1 with a time less than 1:35. To do this, go halfway through the mission until you reach the point where you must use the night vision goggles to find the code and unlock the door. When you reach this point after crawling through the crawl space, turn right and climb over the crate. Go forward until you fall off, and there will be a crate directly on your right. Climb it and there will be a zip-line. This will take you to the end of the mission.