Google's challenges take place in the Google Fit app, which is available for Android and Wear OS-powered smartwatches. Once the calendar flips to 2019, you'll be able to join the first month-long challenge that will reward you points when you complete certain activities logged by the Google Fit app. It'll automatically detect walks, runs and bike rides. You can manually record other specific activities, or sync it with an app like Pokémon Go to track your activity while you play.
Google hands out one point per minute for moderate activities like brisk walks and double the points for more intense ones like running or kickboxing. The baseline goal for Fit is 150 points per week, which is enough activity to meet the recommendations of the American Heart Association (AHA) and the World Health Organization (WHO) for physical activity.
Google is also working with 36 influencers from nine different countries who will provide inspiration to get you going. Google didn't make mention of whether you'll be able to compete with others, though it looks like the Fit challenges are more about motivating yourself rather than taking on your friends for the time being.