Strong communication can be a motivator in itself. Demonstrating empathy and compassion can as well. Not treating employees in a 'one-size-fits-all fashion' will allow them to be their best selves and leverage their strongest attributes. Feeling as though one isn't just another replaceable cog in the machine can motivate employees to be consistent in their contribution in the long-run.

In industries like investment banking, private equity, sales etc.  employees are motivated by negative pressure. You are motivated to work 14 hour days and refrain from taking any vacation ever because everyone else does so, and if you don't conform, you will stand out in a negative way (and if you're still young, your higher ups will make it very clear that you'll get laid-off, even though you never agreed to work on those terms). Since these jobs have succeeded in creating a sense of glam, demand is high, and you are made to feel extremely replaceable. So you grind-away, motivated by the filthy rich future that's just out of your reach.

In other industries, employees are motivated by stability – consistent hours, consistent pay, very little change or unexpected events. Most people feel motivated in environments like these because they perform best in a predictable and easygoing life.

These are just two examples, but there's many, many ways to motivate many different kinds of people who find incentive in very different kinds of freedom.