The way to attain compunction is an attentive life. ‘The beginning of repentance comes from the fear of God and attention,’ as the holy martyr Boniface says.
A little fire softens a large piece of wax. So, too, a small indignity often softens, sweetens and wipes away suddenly all the fierceness, insensibility & hardness of our heart.
Compunction comes when you consider how much you have grieved God Who is so good, so sweet, so merciful, so kind, and entirely full of love; Who was crucified and suffered everything for us. When you meditate on these things and other things the Lord has suffered, they bring compunction.