Influence is usually used for if you're on drugs. sometimes people can influence you to do something.
If have taken drugs, you are "under the influence".
one of the members of the band, Green Day, has done drugs and made a song about being under the influence. the band member was Tre Cool.
Jimmy: Man, I'm gonna go drive to my house now
Tom: Didn't you do some drugs?
Jimmy: Ya, ?
Tom: you'll get thrown in jail for driving under the influence.
The power to change, encourage, or make a difference without force.
I was Influenced to be more polite when I noticed someone walking an elderly lady across the street.