“And take up their cross.” That cross is already there, ready, from the very beginning; we need only take it up. But to keep us from believing that we must simply choose any arbitrary cross, or simply pick out our suffering as we will, Jesus emphasizes that each of us has his or her own cross, ready, appointed, and appropriately measured by God. (Dieterich Bonhoeffer, The Cost of Discipleship)
Have mercy on me, O God,
according to your steadfast love;
according to your abundant mercy
blot out my transgressions.
Wash me thoroughly from my iniquity,
and cleanse me from my sin!
For I know my transgressions,
and my sin is ever before me. (Psalm 51:1-3, ESV)