The hands-down best way to motivate employees is to lead by example. Survey after survey of employees across every industry in the economy show that employee motivation plummets when a supervisor or manager is not living up to their own hype. This lack of motivation either forces some employees to leave the company, but even those who stay are not executing anywhere near their fullest potential. If a manager wants “x, y, and z” from their employees, there is no option but for the employees to see those things (preferably in abundance) from the manager himself/herself. Most people have a natural sense for hypocrisy and hypocrisy is one of the few things almost universally disliked by everyone, in private life or business life.
Maximizing your employees capabilities is a great way to motivate employees. There are far too many employees who have managers micromanaging their every move, which communicates that they do not believe in their employees. Nobody likes to be micromanaged. But before a manager lets their employees “roam wild,” the manager should maximize their employees’ capabilities so they are not “doomed to fail.” This means making sure the employees have all of the resources they need to achieve their tasks, allowing them flexibility (via their schedule, work environment, decision making, etc), and clearly communicating expectations/measures of success.
Offering smaller rewards on the way to a big reward once a big project is completed is a classic way to help motivate employees. In modern times there is literature about this or that “new” way of improving motivation, but it is many more times the case than not that employees do not come in to work “pro bono,” aka for free. Employees trade in their time for some sort of compensation, typically monetary, but whatever compensation means the most to your employees, do your best to offer more of it to your employees to improve motivation.