Some feel unworthy of serving Jehovah because they have committed a serious sin. Guilt can be a harsh taskmaster.
وَعَذَابُ ٱلضَّمِيرِ يُمْكِنُ أَنْ يَسْلُبَهُمْ فَرَحَهُمْ وَسَلَامَهُمْ وَقُوَّتَهُمْ .‏