According to Michael Cohen, one of his frequent jobs was renegotiating bills on Trump's behalf.

"A law firm would send an invoice. He didn't believe that the invoice was fair, reasonable or justified, so he would give me the task of renegotiating a specific bill," Cohen said.

Cohen recounted his work repaying approximately 50 vendors related to Trump University at a discounted rate. All but two of the fifty vendors agreed to the discounted rate.

"They just went away," Cohen said of the two vendors.

"Did you pay then?" prosecutor Susan Hoffinger asked.

"No, ma'am," Cohen responded.

Cohen said Trump told him the outcome of the negotiation was "fantastic" and "great."

"How did that make you feel?" Hoffinger asked.

"Like I was on top of the world," Cohen responded.

Cohen told jurors that he began working for Trump after helping Trump with a series of legal favors.

"We ended up overtaking the board and resolving the issue which was to Mr. Trump's satisfaction," Cohen said about the first favor related to a board at a Trump property. "He liked the way that occurred and then continued to ask me if I would assist in other legal issues or matters he had."

"Did he pay you for that work?" prosecutor Susan Hoffinger said.

"No, ma'am," Cohen said

According to Cohen, Trump offered him a job after he presented Trump a $100,000 bill for legal costs related to the earlier favors.

"Would you want to come work for me?" Cohen recounted Trump saying. "I was honored, I was taken by surprise, and I agreed"

When asked about the $100,000 legal bill, Cohen said Trump "asked if I would like to get fired on the first day." The bill was never paid, according to Cohen, who immediately left his law firm to work for the Trump Organization as Trump's special counsel and a senior vice president.

When asked about the kind of work Cohen did for Trump, Cohen responded, "It was whatever concerned him -- whatever he wanted."

Cohen said he reported "just to Mr. Trump."

Michael Cohen briefly introduced himself to the jury, telling them how his father immigrated to California after surviving the Holocaust.

"Four children later, here I am," Cohen said about his parents.

Cohen told the jury that he went to law school at the urging of his family, though he did not want to practice law.

"I wanted to go to Wall Street," Cohen said.

He briefly explained how he acquired wealth with real estate investments and taxi medallions.

"I ended up going into business with a friend of mine who had grown up with me and we started purchasing buildings," Cohen said.

Cohen stood up in the witness box so he could identify Trump in the courtroom.

"He is wearing a blue and white tie," Cohen said while looking toward Trump.

"The people call Michael Cohen," prosecutor Susan Hoffinger said.

Michael Cohen entered the courtroom and took his seat in the witness box.

Donald Trump stared straight forward as Cohen walked into the courtroom. He did not appear to look toward Cohen.

Following the mid-morning break, prosecutor Susan Hoffinger resumed her direct examination by asking Cohen about attorney Robert Costello, who represented him in 2018.

Cohen testified that Costello told him "this would be a great way to have a backchannel of communication to the president in order to ensure you're still good and still secure"

Cohen said that Costello also touted his relationship with Rudy Giuliani, who was close with Trump at the time.

Costello suggested his representation would be "very beneficial for you going forward with this matter."

Cohen said he was skeptical of Costello because he seemed "really sketchy and wrong."

Cohen also said worried that "anything I said to him was going to be spoken and told to Rudy Giuliani."

Jurors saw an April 2018 email from Costello to Cohen, which Cohen said was sent to "reinforce the whole concept of the back channel."

"I am sure you saw the news that Rudy is joining the Trump legal team. I told you my relationship with Rudy which could be very useful to you," Costello wrote in the email.