Exactly What is Everyone Talking About?

My 13 year old sons and I are training for a half-marathon this January.  For some of our training runs we have used a half-mile walking track in a local park.  Frequently while we are running, a walker will join us on the track for a couple of laps.  Almost always, the walker is walking slowly and talking on a cell phone for the entire time that they are walking.  While they are to be commended on at least being out there exercising (albeit not very vigorously), my real question is, what is it that is so important that these people are talking about about it the entire time of their walk?  And my other question is, how is it that the person on the other end of the conversation has absolutely nothing better to do that they are able to stay on the phone the entire time of this walk?  Is it possible that that person is simultaneously walking and talking on a track someplace else?  I simply do not understand what they have to talk that much about.