כִּֽי־פְ֭שָׁעַי אֲנִ֣י אֵדָ֑ע וְחַטָּאתִ֖י נֶגְדִּ֣י תָמִֽיד׃
For I know my transgressions; And my sin is ever before me.
Rashi on Psalms
and my sin is always before me Since I regret [my sin] and worry about it, it is as though it is constantly before me, always.