 It's a striking comparison to the hard work ethic that this country has been built on. Now, if you're wondering who is a millennial, who's Gen Z? Well, millennials are those who are born between 1981 and 96. And Gen Z are those between the ages of born between 97 and 2012. That would make up a good majority of your workforce now between the ages of 12 and 43 as of this year.