YALE psychology professor Laurie Santos had no idea that her course “Psychology and the Good Life” would be such a hit when she launched it earlier this year.

Before the start date, 1,200 students — about a quarter of their undergraduate population — enrolled, making it the most popular course in Yale’s 316-year history.

According to the New York Times the course focuses both on positive psychology — the characteristics that allow humans to flourish, according to Dr. Santos — and behavioural change, or how to live by those lessons in real life.

Or, in simpler terms, how to live a happier life.

“The purpose of the course is to not only learn what psychological research says about what makes us happy but also to put those strategies into practice,” reads the course outline.

“The first half of the course reveals misconceptions we have about happiness and the annoying features of the mind that lead us to think the way we do. The second half of the course focuses on activities that have been proven to increase happiness along with strategies to build better habits.”

Assistant director of digital education at Yale’s Centre for Teaching and Learning Belinda Platt tells Town & Country “Laurie is a rock-star professor ... She came to us with this idea and said, ‘I’m proposing this course that I want to teach on campus, and I’m doing a pilot run with a small group of 20 to 30 students in my residential college. Why don’t you come film it and then we can use that material for an online course?’”

The five online course lectures were recorded in Professor Santos’ home on the Yale campus.

Dr Santos speculated that Yale students are interested in the class because, in high school, they had to deprioritise their happiness to gain admission to the school, adopting harmful life habits that have led to what she called “the mental health crises we’re seeing at places like Yale”.

The online version of the course (which has been rebranded as The Science of Wellbeing) will be accompanied by a mobile app “to track behaviour that contributes to wellness”.

It’s free to enrol and for a $US49 ($63) fee students will receive a certificate as long as they pass all graded quizzes and writing assignments.

If you feel like stretching your brain and taking the course, you can enrol here for the next series which starts on April 30.

It joins 20 other Coursera online classes taught by the Yale faculty.