Speaking on ITV1's Lorraine programme, O'Reilly said that she pursued the case - which stemmed from the decision to drop her from Countryfile when the show moved to primetime - because she felt the need to stand up against age discrimination.
"I have said that I didn't want to become the poster-girl for discrimination and I fear that I might. But for me it was a principal stand," she said.
"I lost my job because of my age, it was something I had no control over, I can't help getting older and the alternative is pretty dire isn't it? So I felt that I had to stand up and say, 'No, you can't push me to one side because of my age'."
O'Reilly added: "And the ageism debate had been going around and around and getting nowhere. I thought it's time that someone outside of the BBC - outside of what I thought - looked at it and made a decision. And that's why I wanted to go to the tribunal and three judges ruled in my favour."
In her first TV interview since winning the ageism case, O'Reilly told Lorraine Kelly that the trial placed a great strain on her health, including sleepless nights and problems with her heart.
"I was pacing the floor most nights at 3am, I couldn't sleep," she said. "I developed an irregular heartbeat. You can't take on the biggest broadcaster organisation in the world without having some emotional and stressful impact."
This evening, O'Reilly will present an edition of ITV1 current affairs programme Tonight on whether television is ageist, including interviews with axed Strictly Come Dancing judge Arlene Phillips and newsreader Angela Rippon.
The BBC immediately apologised to O'Reilly after the discrimination case and left the door open to working with her again on future projects.
In the Lorraine interview, O'Reilly confirmed that she is talking to the corporation and would "certainly consider" collaborating again.
"I was impressed that the BBC apologised so quickly and the director general [Mark Thompson] rang me personally to say that he was sorry and I was pleased about that. But we are still talking, we haven't decided on anything yet, although I think we will have to see," she said.
"Can I go back to an organisation which unlawfully took away my job and victimised me? I think I can, I'm a professional. Can those people work with me now that were involved in that decision and victimised me? I don't know, it might be a little bit difficult. So I have to think about all of those things, but I want to get back to work."