I started to run this February with 35 lbs excess weight. Chafing was one of my major obstacles. And yes, I remember the pleasusre when one day suddenly I recognized: wow! there is no more chafing between my thighs.
Actually it can be problem even now, 35 lbs later, under the hot California sun. (Between thighs and shorts, arms and shirts etc.) For me the real elixir to prevent this is Bodyglide. (My tritahloner son recommended it, it prevent chafing even when he had to run/cycle with sand-covered body.)