Summarize:

Millennials generally don't want to delay happiness in return for career advancement, and as such are not willing to sacrifice their personal lives for their work lives. This does not mean that they're not willing to work hard - rather, Millennials will work extremely hard during their defined work hours, but they expect to have their "off" times (such as weekends and nights) free from work. In general, Millennials believe that their productivity should not be measured by the number of hours they work, since someone can work for 8 hours and accomplish next to nothing of significance for the company. Instead, Millennials measure their productivity levels by the quality of the work they perform. For example, a Millennial worker might feel better having finished a huge project in 6 hours than having spent an 8 hour day doing "busy work" or answering emails. Millennials are often stereotyped as "entitled" workers and such a perspective can be hard to debunk from the outside. However, in reality, Millennials simply want to feel like more than a "cog in a massive machine." Instead, Millennial workers want to work on projects that matter to themselves, the company, or the world at large. Give Millennials their own projects or a small piece of ownership over a larger project. Millennials are joining the workforce when there are countless companies and newly-forming startup jobs available daily, so they don't feel the need to stay working at a company whose values don't align with their own. Focus on being ethical and fair, and creating a mission that works to make the world a better place. This won't just help your Millennial workers, but all company employees!
Recognize the way Millennials want to balance their work life with their personal life. Gauge how Millennials measure productivity. Legitimize their work. Provide work that matters.