Everyone's life is different — yet most people still utter one of four common phrases on their deathbeds, according to Pulitzer Prize-winning author and oncologist Siddhartha Mukherjee.

Each of the phrases offers an important lessons for leading a fulfilling and successful life, Mukherjee said during a commencement speech at the University of Pennsylvania last week. "Every person that I've met in this moment of transition wanted to make four offerings," he added.

The phrases are:

I want to tell you that I love you. 

I want to tell you that I forgive you. 

Would you tell me that you love me? 

Would you give me your forgiveness?

People who know they're dying often express some variation of one of those four themes — indicating that they waited until it was late to show their appreciation for others or right their interpersonal wrongs, said Mukherjee, author of the award-winning 2011 nonfiction book "The Emperor of All Maladies: A Biography of Cancer."

Instead, they harbored grudges, lived with unresolved guilt or spent years being too afraid to be vulnerable, Mukherjee explained. The ensuing remorse, stress, poor mental health and even hormonal and immune imbalances can stunt your personal and professional growth, neurobehavioral scientist J. Kim Penberthy wrote in a 2022 University of Virginia blog post.

"Love and forgiveness, death and transition. Waiting [to express yourself] merely delays the inevitable," said Mukherjee, adding that young people should, "take this seriously. You're living in a world where love and forgiveness have become meaningless, outdated platitudes ... They're words people have learned to laugh at."

Coming to terms with the fact that you've wronged or hurt someone can be difficult. Try following these four steps, recommends Richard Cowden, a social-personality psychologist with the Human Flourishing Program at Harvard's Institute for Quantitative Social Science:

Take responsibility for your actions.

Allow yourself to experience negative feelings, like remorse and guilt.

Give a sincere apology and try to make amends.

Learn from the experience and move on.

"It's uncomfortable to admit you've done something wrong, and it's natural to protect one's self-esteem by dismissing what happened or making excuses for your behavior," Cowden told Harvard Medical School in 2022. "[But] it can free you from your past mistakes and help you live more fully in the here and now. You might be surprised how much better you feel if you can work through the process of forgiving yourself."

You can also show appreciation for people by speaking their love language: Take your partner's vehicle to the car wash without them asking, or surprise your mom with flowers. Go out to dinner with your friends or give someone a hug. Simply say, "I love you" or "I appreciate you."

Just make sure you actually mean words like "love" and "forgiveness" when you use them, said Mukherjee.

"I dare you to use these words," he said. "But not as empty clichés, imbue them with real meaning. Do it your way, whatever your way is."

CNBC