“Everything I’m truly proud of in this life has been a terrifying prospect to me. From my first play, to hosting ‘Saturday Night Live,’ getting married, being a father, speaking to you today. None of it comes easy. People will tell you to do what makes you happy, but all this has been hard work. And I’m not always happy. I don’t think you should just do what makes you happy. Do what makes you great.” Those were words of wisdom from “Horrible Bosses” and “It’s Always Sunny In Philadelphia” actor Charlie Day, who spoke at Merrimack College’s Commencement on Sunday. The ’98 Merrimack grad, whose epic speech is now online, was among a pack of celebs who were in Massachusetts to share insights and pick up honorary degrees over the weekend. Fashion entrepreneur Tory Burch spoke at Babson’s commencement on Saturday. “The Big Bang Theory” actress Mayim Bialik and Bill Cosby were each given an honorary Doctor of Humane Letters at Boston University on Sunday.