Zumba Fitness World Party

There are a few ways to obtain this achievement, a couple of which involve other players or accounts creating a challenge and sharing it with you, but these aren't necessary. The easiest way to get this, which avoids relying on other accounts, is to set a goal as you would for yourself normally. Upon creating the goal (and making it as short and easy as possible, for the purposes of this achievement), there will be a 'Share' button in the bottom of the screen. Highlight this, and your friends list will pop up. Choose any gamertag on your friends list (they need not have ever even played this game) to share your challenge with them. Now that the challenge is shared, simply complete it to unlock this achievement.