Ah, oushi, didn't you hear of the "4 Forces"/ 4 Powers" ?
I don't find any link, but confessing is a means for clearing up and losing bad Karma.
The means is to say it openly (at least to oneself), don't hide it, regreting it(1), don't want to do it again (2), asking the Buddhas & Bodhisattvas for supporting this task (3) and dedicating the merits of ones sadhanas to this task (4).
But mainly it is about harming others. To be no Buddhist doesn't harm anybody. To say a lie harms.
If one only harms himself, it is a harm too.
I can confess right here, that in my real life I have to work on right speach and on concentration on my duties...
Because, if our mothers, who have been kind to us
From beginningless time, are suffering,
What can we do with (just) our own happiness?
From 10th of 37 Bodhisattva Practices