The link that is made between our not seeing the commandments as grievous and our overcoming the world shows us that obedience and a right attitude to God’s authority over us are at the heart of the great battle that we wage with the forces of darkness. Much of Satan’s effort is focused on stirring up resentment towards God, and our residual sinful nature makes us highly susceptible to this.
Keeping God’s commandments involves a negative element: not obeying the world’s suggestions, not following its fashions. No one can obey God who does not engage in this negative element of putting off the old man as well as putting on the new.
As Candlish says, here is a clear test of the world: it is anything which tends to make us see the commandments of God as grievous. When the believer encounters the world he senses it sapping his strength, so that prayer and Bible study become harder or even a chore, for having given way to the world to some degree he has lost part of the love that he had for God.