I'd like to participate in group challenges like Running Distance/Walking Distance etc but at the same time I don't want to make my activities public to the group. Right now my stats are all at zero. However, I see that there are people in the group, whose kms ran are non-zero while when you go to their profile it is said they "only share some information publicly" and their activities don't show up in the group feed. How do I achieve the same?