Some of the levels are so-called Burrow Run levels, where you automatically keep running right and you can jump, burrow etc. First chance to get this achievement is in the first hub world. After completing the first level, Heavy Heads, go across the bridge and look right. Enter the level Dungeon Run, complete it and pop goes the 5G! Super easy, but below is a video of the level. Credit of the video goes to Nintendo Village.