Challenges are available to participants based on their group. If your group admin elects to run a challenge for your team, you'll see it pop up on your Dashboard.
Just click on View All Active Challenges under the Leaderboard and To-Dos:
In the Active Challenges, you'll see the challenges that your team is participating in as well as the ones that have been completed.
When you click on a challenge, you'll be given the options to Track or view the Leaderboard:
Tracking the Challenge takes you to the area of the Health Diary where you document your participation.
Clicking on the Leaderboard shows you who is ahead of you in the competition!
You don't HAVE to be in a challenge - it's available to you if you want to participate and you'll earn points every time you track! And you don't have to sign up, just start tracking and make a note to track every day. That way you'll make the most of the challenge as you work towards a healthier you!