The struggles and hardships of life, and our sinful failures, can bring us to a point where we don't feel like overcomers. John calls us not to trust our feelings, but to trust Jesus who truly calls us overcomers.
You can read the written sermon here:
https://www.sermoncentral.com/sermons/8-being-overcomers-allan-quak-sermon-on-failure-249092?ref=SermonSeriesDetails