Joseph Ahrens is a plumbing superintendent.Courtesy of Joseph AhrensJoseph Ahrens is a plumbing superintendent in San Diego who makes $140,000 a year.Inspired by his brother, Ahrens started a plumbing apprenticeship at 19 and worked his way up.He tells apprentices who work for him to care for their bodies and finances to succeed as plumbers.This as-told-to essay is based on a conversation with Joseph Ahrens, a 39-year-old plumbing superintendent based in San Diego.