When "light sins" aren't so light

While he is in the flesh, man cannot help but have at least some light sins. But do not despise these sins which we call "light": if you take them for light when you weigh them, tremble when you count them. A number of light objects makes a great mass; a number of drops fills a river; a number of grains makes a heap. What then is our hope? Above all, confession.
St. Augustine, quoted in #1863

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Sin creates a proclivity to sin; it engenders vice by repetition of the same acts. This results in perverse inclinations which cloud conscience and corrupt the concrete judgment of good and evil. Thus sin tends to reproduce itself and reinforce itself, but it cannot destroy the moral sense at its root. #1865

From The Catechism of the Catholic Church in the section looking at mortal versus venial sins.

I have to admit there is a certain comfort in knowing I'm clear of mortal sin. Unfortunately that gives a tendency to think of venial sins as light and not worth worrying about as much. Until we consider the points made above. I think of gnats which seem so little and "light" until one is caught in a cloud of them. What venial sins are clouding sight and mind until I can't even imagine life without them?