At the end of their lives, people tend to reflect on things they wish they'd done differently.

Many wish they'd expressed more love and forgiveness, and use their last words to show their appreciation for the people in their lives, oncologist Siddhartha Mukherjee recently said during a commencement speech at the University of Pennsylvania.

Other people regret not doing enough for themselves, according to Bronnie Ware, author of the 2011 book "The Top Five Regrets of the Dying" and a former palliative care worker. Ware spent eight years administering aid for people battling serious illnesses, many of which turned fatal.

She paid attention to the guilt and remorse people expressed on their deathbeds, and thought there was a "big lesson" people could learn from them, she told British radio program "The Chris Evans Breakfast Show" last year. Her book details the five phrases she heard most frequently:

• I wish I'd had the courage to live a life true to myself, not the life others expected of me.
• I wish I hadn't worked so hard.
• I wish I'd had the courage to express my feelings.
• I wish I had stayed in touch with my friends.
• I wish that I had let myself be happier.

The first regret is the one she heard the most often.

"When people realize that their life is almost over and look back clearly on it, it is easy to see how many dreams have gone unfulfilled,' Ware wrote in a blog post. "Most people had not honored even a half of their dreams and had to die knowing that it was due to choices they had made, or not made."

You might choose a college major, career path or job because your parents want you to. Maybe you've sacrificed your dreams of traveling the world to stay close to your loved ones. Save yourself a lifetime of remorse by putting your interests and happiness first when making decisions, Ware advised.

As for the regret of working too hard, 78% of U.S. workers are currently leaving vacation time on the table and overextending themselves to get ahead professionally, according to a recent Harris Poll of 1,170 American workers.

Prioritizing your job above all else makes tending to your mental health and relationships more challenging. Billionaire Microsoft co-founder Bill Gates learned that the hard way, he said during a commencement speech at Northern Arizona University last year.

"When I was your age, I didn't believe in vacations. I didn't believe in weekends. I didn't believe the people I worked with should either," said Gates, adding that he didn't realize "there's more to life than work" until he became a dad.

"Don't wait as long as I did to learn this lesson," he said. "Take time to nurture your relationships. To celebrate your successes. And to recover from your losses. Take a break when you need to. Take it easy on the people around you when they need it, too."

Pouring time and attention into your friends and family, putting your interests first and staying true to yourself all play a role in your overall happiness and life satisfaction, according to Ware.

Most people don't come to realize that until it's too late, she wrote in her blog post.

"Many did not realize until the end that happiness is a choice. They had stayed stuck in old patterns and habits. The so-called 'comfort' of familiarity overflowed into their emotions ... When deep within, they longed to laugh properly and have silliness in their life again," she wrote.

"Life is a choice," Ware added. "It is YOUR life. Choose consciously, choose wisely, choose honestly. Choose happiness."

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