Valerie Harper became famous playing the shoot-from-the-hip, loud-mouthed New Yorker, Rhoda Morgenstern, on the '70s hit "The Mary Tyler Moore Show," and her own spinoff, "Rhoda."

Four decades later, and now facing a diagnosis of terminal brain cancer, Harper, 73, is maintaining the same loud-mouthed, positive attitude that endeared Rhoda, and Harper herself, to millions of TV fans in order to make the most of whatever time she has left.

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"Don't go to the funeral until the day of the funeral. Live this day," Harper said today on "Good Morning America," summarizing the outlook she's adopted since learning Jan. 15 that she has leptomeningeal carcinomatosis, a rare condition that occurs when cancer cells spread into the fluid-filled membrane surrounding the brain.

Harper appeared on the cover of People magazine last week to announce her diagnosis and has made a round of media appearances since, a decision she said is part of a greater purpose she believes she now has.

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"While I am feeling good…and while I can talk to people, I thought let the extended family know at the same time," Harper said on "GMA." "And then let's discuss it because we are all terminal. We really are. We have a lot of fear around death and I thought maybe I can help somebody."

"Tony and I decided we would do this because I want people to be less scared," she said, referring to her husband Tony Cacciotti. "I want them to know the new realm of cancer, that you can die with cancer but not of it."

WATCH: Valerie Harper, Sitcom Legend, Looks Back

Doctors have told Harper she may have just three months to live but the Emmy-award winning actress - who battled lung cancer in 2009 - says she is moving forward with her life, continuing to promote her recently released memoir, "I, Rhoda," and even considering new jobs.

"I'm going to the movies with my husband. I'm living very normally thanks to some stabilizing [medication], two pills only, morning and night," she said. "People have been offering me jobs. I think I can do them. I mean, right now, so far, if they were willing to take the chance."

The actress, who gave up the lead role in the national tour of "Looped" after her diagnosis, says she is also buoyed by the outpouring of support she has received from fans and her former co-stars.

"I want to tell them how supportive and loving and exciting it is to feel this in the here and now and that's it," Harper said. "This is the joy of this. If I was gone you'd be having memorials. This way we can share back and forth."

Harper, well-known for the optimistic attitude that got her through lung cancer and decades in show business, is also not giving up hope.

"When I first had the cancer four years ago my husband said, 'Why you Val?,' and I said, 'Why not me?'" she said. "I have a wonderful husband. I have health insurance from my union. I wish it for all Americans. Everybody should have the chance I have of extending my life."

"Tony is saying, 'Well extend it long enough so something comes up that is a cure' and my doctor said, 'It's incurable, so far,'" she said. "And I love that, not a shred but a possibility. We all need to live in infinite possibility."

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