John Wesley addresses the heaviness experienced by believers through manifold temptations, emphasizing that such heaviness does not equate to darkness of soul. He explains that believers can endure heaviness while still possessing faith, peace, hope, and joy, as these elements coexist even in trials. Wesley outlines the causes of this heaviness, including physical ailments, poverty, and the loss of loved ones, and he highlights that these trials serve to strengthen faith and holiness. Ultimately, he encourages believers to view their heaviness as a means to grow closer to God and to prepare for eternal glory.