Diagnosed with ovarian cancer at age 23, the former MTV reality star had an ovary and fallopian tube removed. Then, in 2012, the cancer came back, and Brown went through another round of treatment. She shared her journey in a candid blog on PEOPLE.com.
Now 30 and cancer-free, Brown says the aftermath of her public fight still follows her wherever she goes.
"I'll go out to a club or to party and be having a good time," she tells PEOPLE, "and then suddenly someone will come up and start talking about how their sister had cancer. It changes the mood! But, believe it or not, it doesn't really bother me. In fact, I welcome it. I went public with my journey for a reason, and I really do want to help people."
She adds: "Some people just want to talk about it. That's part of the process. They need to talk to someone who has been there. And I have definitely been there!"
PEOPLE caught up with Brown in Celebration, Florida, on Saturday at Hearts of Reality, a gathering of more than 100 reality stars to raise money for Give Kids the World, an organization that grants wishes to children with life-threatening illnesses.
Brown – along with The Bachelor's Juan Pablo Galavis, Nikki Ferrell and others – mingled with the children before hosting a fundraising autograph session. The weekend, sponsored by Lexin Capital, raised more than $100,000 for the charity.
Brown says her medical history has helped activate her charity work. "For one thing, I never say no to anything anymore," she says. "Like this event. When I hear about a way to help children who are fighting cancer, I have to try to come to it. How could I not be here?"
To date, Brown's health is in check and she remains cancer-free.
"I go in every two months for tests," she says. "So every two months, it's a little nerve-racking as we see if everything's okay. It is really a reminder that this is my life. This is what I've got. Cancer has changed who I am. It sounds like a cliché, but I've only got this one life, and I need to live every day to the fullest. I'm a lot more appreciative of things now."