You can also use apps like strautomator to be more selective in what other people can or can't see. For instance, I use it to mute all walks and activities under a certain amount of time (basically warm ups or things that get aborted for whatever reason) so that they don't show up on people's feeds. That allows me to do challenges that require things not be private, but still keep me from spamming people's feeds with simple stuff. When I was recovering from getting hit by a car, several people were well-meaning by commenting on every walk I did, but it got annoying being congratulated for walking half a mile (even though it was a big effort at the time).