Paul is telling the Thessalonians that abstinence from sexual sin is tied directly to how well they control their bodies. Chuck Swindoll illustrates this well: Abstaining begins with “possessing” our own vessels, that is, knowing our own bodies—how our sex drives function, what weakens our self-control, and what strengthens it. Possessing our bodies involves admitting temptations we can’t handle and avoiding those enticing situations. Certain conversations with coworkers may lure us, and friendly