Sometimes we make a choice that we don't want to but have to because of the collective circumstances that we are in .. Some decisions made then, rip your conscience to shreds...
Naturally so, it re-builds itself.. in the best way it sees fit.. moulding itself into a form where if a similar decision were to be forced down it again, it could do so in a heart beat.. without affecting itself, the conscience.
The conscience then build a wall... It throws up barricades around itself.. solidifying... thinking it's protecting itself.. which might be true on the immediate .. but in the long run.. it's only digging it's own grave..
Bhishma Pitamah, given iccha mrityu would have lived forever... yet he was killed.. a thousand arrows.. by his own conscience...