Valerie Harper, 73, recently announced that she has been diagnosed with a rare form of terminal brain cancer.

Harper is best known for playing Rhoda Morgenstern, the quick-witted roommate and brazen buddy of Mary Richards on the 1970s sitcom, "The Mary Tyler Moore Show," and star of the show's eventual sequel, "Rhoda."

Truth is, no matter who you are, or what life stage you're currently in, every woman needs at least one "Rhoda" in their lives; someone who embodies that special mix of sarcasm, candor, wit and loyalty that come together to make an irreplaceable companion.

Here are 5 reasons every woman needs a Rhoda:

1. She'll help you believe in a better tomorrow

Rhoda: "Mary, you're having a lousy streak. I happen to be having a terrific streak. Soon the world will be back to normal. Tomorrow you will meet a crown head of Europe and marry. I will have a fat attack, eat 3,000 peanut butter cups and die."

No one can (or should) be a Positive Polly 100 percent of the time. It's an indisputable fact of life that you will get knocked into the dirt a few times. When this happens, you need to have someone around who can pick you up, dust you off, and get you ready to face another day. The best kinds of friends are those that can set you on the path towards finding your inner source of optimism. Extra points are awarded for buddies like Rhoda, who can flavor their support with a dash of good humor.

2. She knows what it's like to have a complex relationship with one's mother

Rhoda: "I think she's holding a grudge because I didn't go into the profession she wanted."

Mary: "What's that?"

Rhoda: "A housewife."

Everyone's relationship with their mother is different. Mothers can be notoriously hard to please. This often stems from a place of deep love; they only nag because they want the best for their children. Other times, mothers can be a source of constant negativity and deflating put-downs. No matter what kind of mom you have, the two of you won't always hit it off. When mothers and daughters fight, the chaos that ensues can mimic that of a raging hurricane. During these troubled times, having a friend who understands what you're going through, someone who you can be open and share your feelings with, is an invaluable asset. For example, these priceless individuals can do wonders to help you cope with taking care of parents you don't like.

Browse Our Free Senior Care Guides

3. She'll help you solve your problems

Mary: "Oh Rhoda, chocolate doesn't solve anything."

Rhoda: "No Mare, cottage cheese solves nothing. Chocolate can do it all."

Rhoda does have a point. Not only is chocolate a tasty indulgence, it also may have certain health benefits. Still, not every problem can be solved with a Snickers—that's what friends are for. A non-judgmental pal can help you talk through different solutions to a problem, sometimes offering suggestions, and other times just letting you bounce ideas off of them. Just remember the importance of reciprocation; you have to make time to help your friends solve their problems too. This can be especially tricky for women who are part of the so-called, "Sandwich Generation," trying to balance elder care with other relationships, such as friends and family.

4. She'll offer a healthy dose of brutal honesty

Rhoda: "Mary, I thought you knew. Your parties are, uh, disasters. I mean, I thought you knew. How could you not know that?"

Honesty is a highly-undervalued trait that is absolutely essential in a good friend. Just as you need friends willing to extend a helping hand when you really need it, you also need comrades who will stand there, encouraging you to get up on your own. It's easy to become so mired in your own problems, or stuck in your own mental rut of feeling sad, guilty, angry, etc. In these instances, you don't necessarily need a helping hand, you need an outside voice to tell you that enough is enough—it's time for you to snap out of your funk and take control of the situation. Ideally, this voice will come from someone who you know loves and cares about you. A great friend is one who can sensitively point out your shortcomings and encourage you to find a way to overcome negative emotions that are preventing you from growing as a person.

5. She'll chase away the critics

Phyllis (Mary and Rhoda's sarcastic landlady): "I just thought I'd see what you swingin' singles do for fun."

Rhoda: "Same as you—sit around and wonder what it would be like to have a happy marriage."

There are always going to be people who find fault with practically everything you do. Whether it's a family member, an acquaintance, a co-worker, or a crotchety landlady like Phyllis, these people are draining to be around. That's why you need a friend like Rhoda who can offer just the right dose of wit and aggression to let these individuals know that their brand of negativity is not welcome in your life. These kinds of friends can help teach you the value of setting boundaries with parents who are abusive, or other people who are harassing you.

Embracing the future with an open mind

But, Harper's influence extends far beyond her roles of sassy sidekick and spinoff success.

It is her indomitable spirit that inspired an entire generation of women. And, since going public with her diagnosis, it's clear that no disease has enough power to snuff out that spirit.

In an interview with "Today" show correspondent, Savannah Guthrie, Harper had this to say about her prognosis:

"It feels awfully damn good to be open about it, face it and see what you can do. If you die, you're not a failure. You're just somebody who had cancer, and that's the outcome," she says, adding "I'm not dying until I do."

Maybe, just as every woman needs a friend like Rhoda, so too does every woman need a spirit like Harper's. An inner voice that constantly encourages you to, "Keep your thoughts open to infinite possibility and keep yourself open to miracles."