Laura Ling and Euna Lee were pardoned by North Korea after being convicted and sentenced to 12 years in a labor camp for entering the country illegally.
Clinton arrived in North Korea earlier this week and returned with the two women Wednesday.
"If Bill Clinton had not gone over there, Laura and Euna would still be there," Lisa Ling, Laura's sister, told CBS' "The Early Show" Friday, adding that Clinton spent less than a day in North Korea and that his goal was "solely" to win the release of the journalists.
At an event in New York Thursday, Clinton said:, which I was profoundly honored to do as an American and as a father," Clinton said. "I wanted those young women to be able to come home. And I wanted our two countries to have the ability to decide where to go from here."
As for her sister's return, Ling said her and her family "have all just spent two of the best days of our lives."
Ling added that Laura's stories so far about her time in captivity have been "fascinating," and that she is eager to talk more in the coming days.
Lisa Ling told CNN Thursday that her sister and Lee briefly walked on North Korean soil before being captured and detained for months in that communist country.
"She said that it was maybe 30 seconds and then everything got chaotic. It's a very powerful story, and she does want to share it," Lisa Ling said.