Wanjira Mathai has more than 20 years of experience advocating for social and environmental change on both local and international platforms.

Regina Hartley thinks that those who don't always look good on paper may be just the person you need to hire.

In her book "Citizen Scientist," Mary Ellen Hannibal traces the origins of today’s tech-savvy citizen science movement back through centuries of amateur observations by writers and naturalists.

Lorna Davis inspires, coaches and provokes leaders to use business as a force for good.

Bruce Feiler is a leading voice on family, work, transitions and meaning.

At Purpose, Jeremy Heimans strategizes how to harness new social, economic and technological models to build movements with impact.

BCG’s Martin Danoesastro supports organizations to change their ways of working at scale, enabling them to succeed in an increasingly digital world.

Tilak Mandadi and his global team at Disney are integral to converging the physical and digital worlds to create magical memories for more than 150 million annual guests at Disney’s theme parks, hotels, cruise ships, retail stores and restaurants -- and bringing that magic home to millions more with games, books and digital experiences.

Geena Rocero is a professional model for fashion and beauty companies around the world. And she uses her platform to share a powerful story.

Jennifer Aaker is a behavioral scientist focused on understanding what creates meaning vs. happiness in life.

Ashley M. Grice believes in the power of wonder and unconventional thinking to disrupt industries and the status quo.

Hilary Cottam wants to redesign the welfare state using the power of relationships.

Jan Rader is a firefighter and a nurse.

Rha Goddess is a cultural innovator, social impact strategist and creative change agent. She works with leaders and organizations to realign their missions in ways that are more purposeful, profitable and impactful.

Alex Edmans uses rigorous academic research to influence real-life business practices -- in particular, how companies can pursue purpose as well as profit.

At Clean Start Kenya, Teresa Njoroge builds bridges connecting the formerly imprisoned to the outside world and vice versa.

Using fMRI imaging to watch the human brain at work, Nancy Kanwisher’s team has discovered cortical regions responsible for some surprisingly specific elements of cognition.

Stuart Firestein teaches students and “citizen scientists” that ignorance is far more important to discovery than knowledge.

Surely not the only science career based on a museum tour epiphany, Paul Sereno's is almost certainly the most triumphant. He's dug up dinosaurs on five continents -- and discovered the world's largest crocodile, the (extinct) 40-foot Sarchosuchus.

Bassam Tariq delights in making eclectic career choices. A blogger, a filmmaker, and a butcher's shop owner, the common theme linking everything together is his boundless celebration of humanity.

Rebecca Henderson is obsessed with finding solutions to climate change.

Brewster Kahle is an inventor, philanthropist and digital librarian. His Internet Archive offers 85 billion pieces of deep Web geology -- a fascinating look at the formation of the Internet over the years, and a challenge to those who would keep knowledge buried.

Nancy Frates and her family have raised a projected $160 million for ALS research in 2014. How? They kicked off the ALS Ice Bucket Challenge to honor 29-year-old Pete Frates.

Nic Marks gathers evidence about what makes us happy, and uses it to promote policy that puts the well-being of people and the planet first. He's the founder of the Centre for Well-Being at the UK think tank New Economics Foundation (NEF).

One of the true luminaries of personal computing, Alan Kay conceived of laptops and graphical interfaces years before they were realized. At XeroxPARC, Apple, HP and Disney, he has developed tools for improving the mind.

Maria Popova thinks and writes about science and art, poetry and philosophy, children's books and our search for meaning -- about what it means to live a decent, inspired, substantive life of purpose and gladness, wonder-smitten by reality.

Gala Marija Vrbanic is a leader in the field of contactless and cyber fashion.

A neuroscientist and engineer, Daniel Wolpert studies how the brain controls the body.

Pastor Rick Warren is the author of The Purpose-Driven Life, which has sold more than 30 million copies worldwide. His has become an immensely influential voice seeking to apply the values of his faith to issues such as global poverty, HIV/AIDS and injustice.

Dr. Valerie Purdie-Greenaway teaches, conducts research and consults with global leaders to help them develop and foster diverse and inclusive work.