Nobody starts as a liar. They start with small ones that worked.

Dishonesty gets built by reinforcement rather than by decision. A small untruth gets you out of something, nothing bad follows, and the next one comes easier because the first proved the method works. Nobody picks the identity. It accumulates out of a hundred moments that each looked too minor to bother about.

The useful place to interrupt it is while it is still small and costs almost nothing. Catch one convenient line this week and correct it inside the same conversation. Watch how little actually happens when you give the plain version instead.