Repentance is a gift that is of and, therefore, from God (e.g. 2 Tim. 2:25b). Repentance, is not, nor can it be, something that we, as congenitally sinful human beings (e.g. Ps. 51:5; Eccl. 7:20; Rom. 3:23; 5:12), generate autonomously within ourselves, knowing that it is wholly against our nature, that is, in our unregenerate state, to want to be right with a holy God to begin with. Repentance, whether unto salvation (Mk. 1:15) or from sins we commit (Acts 3:19; Rom. 2:4), is something God Himself must do within us. Darrell B. Harrison.
The first step in having assurance of salvation is believing that the God who saved you to begin with (1 Corinthians 1:30; Ephesians 2:5-8; Titus 3:5), is not a liar and, as such, can be trusted to keep you saved from the moment you first believed until the moment you take your last breath in this life (Psalm 48:14; 2 Timothy 1:9; Jude 1:24). If you don’t believe that, you will most assuredly struggle with assurance. Darrell B. Harrison.
https://www.gty.org/library/sermons-library/GTY155M/the-faith-that-doesnt-fail