I want to impress my girlfriend so I'm going to tell a lie.
Why do you feel the need to lie to her?
I want to change my girlfriend's perception about me.
Telling lies is wrong. Eventually the truth will come to light and others will not trust you.
What doesn't kill you makes you stronger. Lying will help me in the end.
Lying is a sign of weakness. You shouldn't have to exaggerate who you are to win your girlfriend's affections. Focus on improving yourself, and if she doesn't like you, it's her loss.