He'd just say this was the only thing that would keep him normal, pulling out all the anger in the gym, Bagos told The Associated Press.
Vargas also complained about bad experiences with women, Bagos said.
Vargas became more closed off recently, Bagos said. When Bagos tried to say hello, Vargas would abruptly walk in the other direction.
"I thought he was going through problems and I kept away from him," Bagos told AP.
The tragedy in Hialeah has garnered national attention including in Newtown, Connecticut, the town rocked by the December mass shooting at Sandy Hook Elementary.
The non-profit organization Sandy Hook Promise, formed by community members in Newtown, issued a statement on the Hialeah killing spree.
Our hearts are broken, the statement said. Our spirit is not. Sending prayers and condolences to the victims and families of the Hialeah, Florida mass shooting. Another tragedy that invites us all to reflect on what individual and collective changes we can make as a nation to save lives.
Police still arent certain of the motive for the killings, though they think it may have started as a dispute with the building managers, the Pisciottis. The couple, ages 79 and 69, were to celebrate their 30th wedding anniversary next month.
As the couple arrived at the front door, Vargas mother, Esperanza Patterson, 83, screamed: Get my son out of the apartment!
Mariano Arias, 46, who lives on the buildings second floor, said he heard her scream, then gunfire. I hit the ground, he said.
Vargas fired about 20 times, police said, shaking nearby apartments. The Pisciottis fell outside the door. Patterson ran outside as smoke billowed from the apartment and draped herself over the bodies, said a witness who did not want to be identified.
Vargas returned to his apartment, went onto the balcony and began firing. One of those bullets struck Carlos Gavilanes, 33, who lived across the street.
Run! Gavilanes cried out to his son, who was just steps away. He collapsed with his son at his side.
Vargas then marched down to a third-floor apartment, kicked in the door and killed Patricio Simono, 64, and his girlfriend, Merly Niebles, 51.
Her 17-year-old daughter, Priscilla Perez, ran into the bathroom and climbed into the tub, but Vargas followed, taking her life as well.
On Sunday, Hialeah detectives continued to talk to Vargas mother, looking for clues on what sparked her sons rampage.
The elderly woman told detectives her son did not have a girlfriend, although a neighbor said that during the hours-long negotiations with Hialeah police that started Friday night, he heard Vargas tell police he wanted to speak to his girlfriend.
The hours of tense negotiations took place as Vargas pointed a gun at two other neighbors, Zoeb and Sarrida Nek, who he had taken as hostages in apartment 525.
Neighhbor Margarita Reyes said she saw Zoeb run out of his apartment barefoot after hearing the initial gunshots.
"We went inside, but he stayed there," she said.
She and others think that because Zoeb remained outside in the spot where he usually had his morning cigarette and tea, with his door open and wife inside, Vargas spotted him and forced him inside 525.
Police then watched as the Neks pleaded for their lives, weeping on their knees in their apartment.