When you stand 5 meters away from the mirror, your image appears
to be 5 meters behind the glass.
When you stand 1 meter away from the mirror, your image appears
to be 1 meter behind the glass.
When you walk towards the mirror at 1.2 m per sec, your image appears
to approach the glass from behind it at 1.2 m per sec.
The image is approaching YOU at 2.4 m/s.