Set in the picturesque venue of the Munro Boutique hotel in Houghton, Johannesburg, the Mzansi’s Sex.
Modise, originally from Eshowe in KwaZulu-Natal, attended many auditions before she got her break in January 2005.
"I remember borrowing a friend's suit and going to auditions in Durban.
"I was desperate. In 2005 the Khethiwe Buthelezi role came up and I gave it my all. The producers told me they were giving me three months to prove myself," Modise said.
Since then she has proven that she is not only intelligent but brings maturity to her role.
"Playing the role of Khethiwe Buthelezi is no child's play. Even after seven years the role is still challenging," she said.
As much as the role helped launch her acting career, Modise said it had pushed her to grow, both as an actress and a person.
The downside to the fame brought by the role is the fact that she is always mobbed by people who only recognise "Khethiwe".
Modise's role started small but has grown over the years to become one of the main characters in the soapie.
"The storyline has evolved a lot, which has helped me grow. All the challenges in Khethiwe's life have made me understand life better and see things differently," said Modise.
When her character started, Khethiwe had just been brought to Johannesburg by her brother-in-law, Khaphela Ngcobo, to be a child-minder.
Over the last few years viewers have watched her go through various stages, including being a millionaire, owning a block of flats and falling for heartbreakers and abusive men.
"Khethiwe was a different kind of helper. She came to Joburg with a plan to change her life around. She might have come from a rural area but she wanted to achieve big things," she said.
"All the changes in the character test your ability as an actor, but I would say I have come out tops because I'm a professional. I went to school to study this."
Early this year her fans thought she would leave the popular soapie. Viewers saw the formerly naive village girl turn into a monster - having an abortion and stabbing Dumisani.
"Khethiwe had to account for her actions. This was the only way she could learn her lesson. The writers could not send her to jail so they sent her to a mental institution to educate the nation that whatever you do there are consequences," said Modise.
She said some of the scenes were very emotionally draining, especially scenes about abuse.
"The trick about doing these scenes is to try to be very convincing. Considering television's influential role, any mishaps could have catastrophic consequences.
"I know that somewhere out there is a woman who is being abused, so I had to be convincing," she said.
Modise said there are qualities that she likes about her role as Khethiwe.
"Khethiwe is a very trusting but naive person who always puts other people first. Her choices in life are often wrong. She is impulsive but all in all she is a good person who loves to help others," she said.
For Modise, it all started when she was still at boarding school in KwaZulu-Natal.
"When our teacher introduced us to drama, he said we could make a living out of acting.
"I had wanted to be a doctor since I was good in mathematics, science and accounting, but here am I now," she said.