The 17-year-old started NYC Says Enough, which is dedicated to combating gun violence and holding politicians accountable.
It was the idea of then-16-year-old organizer, Arielle Geismar. She came up with it after posting on Facebook, asking how she could help and whether anyone else was interested.
"I went to bed like, 'No one’s gonna respond.' And then I woke up and I got hundreds of messages of people saying, 'Let’s do this, I’m ready,'” Geismar told InsideEdition.com.
"I remember thinking, 'Wow. This is power. This is youth power.' And this is where I wanna be."
It was around that same time she started the organization NYC Says Enough.
The nonprofit is dedicated to preventing gun violence and holding politicians accountable for tougher gun legislation. The idea came to her after the 2018 massacre at Marjory Stoneman Douglas High School in Parkland, Florida, that took 17 lives.
"The pain is felt by a lot of people," Geismar said. "It's scary to think that it's going to continue. We know in our hearts that it's gonna happen again. It still hurts every time it does."
The recent mass shootings in El Paso, Texas, and Dayton, Ohio, where dozens of people were killed within hours of each other, unfortunately illustrate why Geismar decided to take action.
"The one in El Paso, we know that this was a white supremacist who wanted to target people of the Latinx community," she said. "That's part of the hatred that we see in 2019 and for some reason, it's up to us as a generation to be solving it."
Geismar's generation is one that grew up witnessing mass shootings entirely too often.
"Sandy Hook happened when I was in middle school. And I just kind of accepted it as an inevitability. Like, this is just going to happen."
At just 5 years old, Geismar said she started practicing mass shooting drills in school.
“I run and hide and I literally end up thinking, 'Is this real?' It's as ingrained in me as learning in shapes and colors were,”
Her work as an activist and organizer earned Geismar, along with 15 other teenagers, the 2019 Diller Tikkun Olam Award and $36,000.
The prize recognizes Jewish teenagers who have shown an outstanding commitment to social good.
"It's at the center of this Jewish value that we have the power to change the world. And not only do we have to be listening first, we have to be working as a collective together in order to make the world a better place."
Geismar said she will use the money to continue combating gun violence, donating some to charities that do the same work, and for her education.
Soon, she will start her freshman year at George Washington University. Instead of being filled with excitement, she's wracked with anxiety.
"I think that going back to school is scary. It brings the inevitability of a new school shooting. It brings kids being scared from the walk to school or the walk home from school in communities that don't necessarily look like mine."
Like a true fighter, she also sees the good in it.
"It also brings the opportunity for new organizing opportunities," Geismar said.