(CNN) The Florida man who pleaded guilty to mailing explosive devices said in a letter to a federal judge that attending a rally for President Donald Trump "became like a new found drug."

Cesar Sayoc has admitted to sending pipe bombs to CNN, and various Democratic officials and donors. He pleaded guilty last month to 65 felony counts, including using weapons of mass destruction in an attempted domestic terrorist attack.

In the handwritten letter filed Tuesday in the US District Court for the Southern District of New York, he told a judge that "the first thing you here (sic) entering Trump rally is we are not going to take it anymore, the forgotten ones, etc."

At those events, he said, he came into contact with all kinds of people. "You met people from all walks life ... color etc," he wrote. "It was fun, it became like a new found drug."

He also wrote that Trump's self-help CDs reprogrammed his mind, and detailed the negative reaction he got for the Trump stickers on his car, including having his tires slashed and windows broken.

"I laughed at first. It was ridiculous how people were reacting and violence on both sides," he wrote.

Attorney said they had him evaluated

Sayoc told the judge that he was abusing steroids and was using hundreds of vitamins and supplements.

"I was the most scared time in my life. ... Plus I was using heavy amounts of steroids, 274 different supplement and vitamins ... I lost my head, steroids altered my growing anger. I made a bad choice taking them to help ... I lost control of myself and mental state from them."

Defense attorneys said they had him psychologically evaluated and plan to submit two reports in connection with his sentencing: one report by a clinical psychiatrist and another one by a psychiatrist with specialized knowledge to explain how his steroid use likely affected his mental health.

"We believe that these two reports will provide the court with ample information about Mr. Sayoc's mental health," his attorneys said.

In a separate handwritten letter at the beginning of the month, Sayoc told the judge overseeing his case that he never intended for the devices to detonate and the pipe bombs were not intended to work.

"The intention was to only intimidate & scare," he said in the two-page letter to US District Court Judge Jed Rakoff.

Sayoc pleaded guilty last month and admitted to mailing 16 explosive devices in October to various Democratic officials, including Barack Obama, Bill Clinton, Sen. Cory Booker and Sen. Kamala Harris. He also mailed the devices to CNN's offices and major Democratic donors, including George Soros and Tom Steyer.

None of the devices detonated and no one was injured. He faces a maximum sentence of life in prison and is set to be sentenced on September 12.