i am doing on it vs i am doing it

Some examples from the web:

• Trust me, I am not not doing it on purpose.
• I'm not at liberty to divulge exactly what I am doing on C Deck.
• And you better believe, I am doing it just for me.
• I am doing exactly what a commander in my position would do.
• I think I know what I am doing.
• I am doing some academic research.
• I know what I am doing and why.
• It's just what I am doing.
• That is what I am doing, despite being razzed at night.
• I am doing the bill for these charming people who are in a hurry.
• I am doing this because I am worried of Han Yoo Ra.
• Listen, I am doing everything I can to fix this.
• Trust me, I know what I am doing.
• Like I am doing with this neighbor woman.
• That's exactly what I am doing again.
• I am doing him a favor and giving him an easy way out.
• I am doing it for Thea.
• Everything that I am doing is backfiring.
• I am doing this because I believe that Bauer is telling the truth.
• But... you just have to believe that everything I am doing is justified.

Some examples from the web:

• And you better believe, I am doing it just for me.
• I am doing it for Thea.
• And I am doing it with your belt.
• Maybe not, but I am doing it.
• I am doing it because I'd rather have one person who really, really loves our product than a thousand totally satisfied customers.
• On the other hand, I am doing it anyway... so let me suggest before you talk divorce, at least consider a separation.
• Mr President, this is the first time I have given an oral explanation of vote, so I hope I am doing it correctly.
• And you better believe, I am doing it just for me.
• I have wanted to be in this business ever since I was a little girl, and here I am doing it.
• I know this may not be the right place, but I am doing it anyway.
• I'm kind of happy that I am doing it, but it's going to be a very interesting reunion.
• I can't stand lying to my wife. I am doing it more, it disgusts me.
• In the hopes that they'll open up, But maybe I am doing it to make myself feel better.
• I am doing it for the sake of my son.
• I am doing it to you, Malloy.
• I am doing it firstly because I like the European Parliament a lot, but above all because Mr Wohlfart is not here.
• I am doing it with the confidence and hope that you will finally believe it.
• My mom used to do the same thing to me, and I swore I'd never do it to you, but here I am doing it.
• If you wonder why l reiterate this so persistently, you should realize that I am doing it with the confidence and hope that you will finally believe it.
• I am doing it.