"You could literally be anything that you want to be. I'm serious," Mosby said. "If you invest in the time now, you will set yourself up, and your family, your mothers, your grandmothers, in a better situation for the rest of your lives."
Mosby says he got serious about academics at Poly, where he played varsity football while participating in a program through Verizon to prepare minority students for engineering careers. He went to Tuskegee University, a historically black campus in Alabama, where he changed majors twice before settling on electrical engineering.
After graduating in 2002, he moved back to Baltimore to take a job at Verizon. He currently supervises the division that coordinates video streaming.
Within a few years, he had married his college sweetheart, Marilyn Mosby, a Baltimore assistant state's attorney, and purchased a shell of a house in Reservoir Hill. The couple rebuilt it and are raising their daughters, ages 3 and 1, there.
Mosby launched a bid for the 11th District council seat in 2007, losing to Bill Cole, a former state delegate. He dug into community life, becoming president of the Bolton Park Neighbors, Inc. in 2008.
Chet Myers, the current president, said Mosby was instrumental in securing nonprofit status for the Bolton Park group and convincing the city to fence and provide water for a community park on Reservoir Street. Mosby also helped organize the home tour and worked with the community garden, he said.
"He's very organized, and he's always out there in the community," Myers said.
Mosby positioned himself for another run for council, joining the board of the Midtown Community Benefits District and winning a seat on Baltimore's State Democratic Central Committee.
This year, he learned that as part of Mayor Stephanie Rawlings-Blake's redrawing of district boundaries, Reservoir Hill was now in the 7th District. That meant he would face Conaway in the election.
Mosby says he mapped out a strategy early, tapping a close circle of relatives, friends and neighbors to become the core of his campaign. He scored a significant win in snaring the services of the influential fundraiser Colleen Martin-Lauer, who manages finances for the campaigns of Rawlings-Blake, Gov. Martin O'Malley and about half of the council.
He says he called Martin-Lauer relentlessly until she agreed to hear him out. He and his volunteers targeted "super voters" in the district, and, he says, he wore a hole in a pair of shoes campaigning.
Mosby asked his niece to recruit dozens of her college friends to attend Rawlings-Blake's campaign kick-off in June while wearing red Mosby T-shirts — from his 2007 campaign, because he had not raised enough funds for new shirts.
It was in the middle of the summer that Mosby realized his message had gotten through. He knocked on the door of a woman he had never met near Mondawmin Mall and she said, "Oh, it's Nick Mosby."
"I knew then I had it," said Mosby, beaming at the recollection.
In late summer, endorsements started rolling in, including from Rawlings-Blake, O'Malley and prominent union groups.
The campaign has been acrimonious at times. Conaway accused Mosby of "dirty campaigning" for distributing fliers that harped on questions about her residency. Conaway certified that a house in Baltimore County was her "primary residence" on paperwork qualifying the home for a Homestead Tax Credit. She has said she inadvertently made a paperwork mistake. Mosby drew attention to the issue with his campaign fliers.
Conaway has asked federal authorities to investigate the fliers, which she says improperly used an IRS logo, and this week asked for the election to be postponed after absentee ballots for another district were sent to 7th District residents.
Mosby shrugs off Conaway's criticisms, saying voters responded to his persistence and were eager for a new face in City Hall.
"I think this campaign and my victory is more than just the 7th District," he said. "The city is ready for new ideas. It's ready for change."