This time of year, many college and university graduates sit patiently through long graduation ceremonies, fanning themselves in the heat and waiting for the main event: a movie star, celebrity, politician or world leader to deliver words of wisdom.

It's graduation season, meaning many colleges and universities feature speakers who are well-known or well-respected for their accomplishments. The speaker's role is to offer graduates advice about launching into the world.

This year's speeches have been delivered by people such as Chadwick Boseman of the Black Panther superhero movie, International Monetary Fund Managing Director Christine LaGarde, former U.S. Secretary of State and oil executive Rex Tillerson, and America's wealthiest African-American woman and celebrity, Oprah Winfrey.

"You need to know this: Your job is not always going to fulfill you," Winfrey said to graduates at the University of Southern California Annenberg School of Communications and Journalism.

"There will be some days that you just might be bored. Other days you may not feel like going to work at all," she said. "Go anyway, and remember that your job is not who you are. It's just what you are doing on the way to who you will become. With every remedial chore, every boss who takes credit for your ideas — that is going to happen — look for the lessons, because the lessons are always there."

She also advised students to "eat a good breakfast."

Tillerson spoke to graduates at the Virginia Military Institute in Lexington, Virginia, telling them to be grateful for the people who helped them succeed, such as parents and teachers.

He also talked about democracy, transparency and truth.

"It is only by a fierce defense of the truth and a common set of facts that we create the conditions for a democratic free society," Tillerson said. "If our leaders seek to conceal the truth or we as people become accepting of alternative realities that are no longer grounded in facts, then we as American citizens are on a pathway to relinquishing our freedom."

Boseman, star of the blockbuster 2018 Black Panther film, spoke at Howard University in Washington, D.C. — the school from which he graduated, known as a graduate's alma mater. (Former U.S. President Barack Obama spoke to Howard grads in 2016.)

Howard is a leader among historically black colleges and universities, or HBCU, in the U.S., but was recently involved in a corruption scandal involving student aid money. Boseman referred to the scandal and other problems facing students, especially African-Americans.

"Many of you will leave Howard and enter systems and institutions that have a history of discrimination and marginalization," he said.

But, Boseman suggested, those problems can make them better people.

"I don't know what your future is," he said. "But if you're willing to take the harder way … the one with more failures at first than successes . . . then you will not regret it. … Remember the struggles along the way are only meant to shape you for your purpose."

Winfrey encouraged students to vote and take action.

"Pick a problem, any problem, and do something about it," she said. "Because to somebody who's hurting, something is everything."

IMF's Lagarde asked graduates at Claremont McKenna College in Claremont, California, to look further into the future to consider what effect their next choices and actions will have.

She asked the graduates to think about how different the world is now compared to 10 years ago, and how different it may be in 10 years.

"What kind of country, what kind of world, will you help build?" she asked. "What values will you respect? What will drive your life and the lives of others? Ten years from now, when the class of 2028 stands here and prepares to graduate, what will you have done to help them?"