The former "Entertainment Tonight" correspondent and "Dancing with the Stars" co-host tells "ET" that she had refused to believe the lump in her breast was benign, even after numerous doctors told her so.
She said she listened to her body and, finally, saw a specialist who gave her the bad news.
The 40-year-old TV personality said her initial response wasn't "Why me?" Instead, she focused on her daughters, who are 3 and 6.
Harris, who lost her father when he was 50, recalled that he wasn't there to walk her down the aisle.
But Harris said her own prognosis is encouraging. She expects to be around to plan her daughters' weddings. She added, "They better like the dress I pick."