Travers passed away in 1994, 10 years after he, his wife and their son founded the Born Free Foundation.
Today, at the age of 79, McKenna spends most of her time volunteering for the charity.
"I see the mountains that are still ahead to climb over. I see, still, the thousands of animals we never can help. I think if I am talking to a group of people, and I change one mind and heart, I'm thrilled," said McKenna.
The Born Free Foundation started in England, but it sure has grown over the years and it's still expanding to help wild animals.
It has projects in Sacramento, Nairobi, Sri Lanka, a rescue center in India, two centers in South Africa and now it's at work in Ethiopia.
"We're building a rescue education center and a clinic for animals and there's a queue now of animals waiting to come. The foundation stone was laid in February and I'm hoping it'll open early next year," said McKenna.
McKenna has detailed some of her stories in her autobiography, "The Life in My Years."
You could say, a movie called "Born Free" was just the beginning of an epic story still being played out in real life.
"But I have a lot of energy still, and I hope I go on just 'til I drop actually because I can't give it up. I just can't," said McKenna.
Do you want the Eyewitness News team to call you? Get a FREE Morning Wake-up Call and personalized weather report at abc7.com/wakeup