Billionaire philanthropist Bill Gates doled out some free advice to the new university and college graduates among his 34.8 million Twitter followers. 

In 14 tweets dispatched on Monday, the founder of Microsoft said that artificial intelligence, energy and biosciences are “promising fields” for young people who are just starting their careers. 

But his tweets mostly focused on personal growth, telling the future generation of workers and leaders to surround themselves with people who encourage and challenge them. Gates said he measures his own happiness by “whether people close to me are happy and love me, & by the difference I make for others.”

Gates also suggested a book titled “The Better Angels of Our Nature,” which he said was “the most inspiring book I’ve ever read.”

The bestselling book by Steven Pinker outlines how violence around the globe has declined over centuries and puts into context the wars, murders and other violent crimes that occur in the modern era.

Gates, who runs the charitable Bill and Melinda Gates Foundation with his wife, said the idea that the world is getting better, as Pinker argues in his book, “sounds crazy, but it’s true.”

“That matters because if you think the world is getting better, you want to spread the progress to more people and places,” he tweeted.

Since Gates’ tweetstorm, sales of “The Better Angels of Our Nature” surged on Amazon.

Gates wrapped up his advice by tweeting: “This is an amazing time to be alive. I hope you make the most of it.”