The best way to keep my team motivated during long shifts is to constantly check in with them to ensure they are at their best, mentally & physically. A great leader knows the pulse of his/her team and knows when to give more assistance at times and when to apply more pressure to get the job done. In my 25 years in the hospitality industry, I have learned to adapt to each situation differently and become a better listener to enable my team to be the best cooks/chefs that they can be.
The best way to keep staff motivated is to keep a healthy positive work atmosphere. That is to create an environment where staff likes working, keep it professional, and about high-quality output. Recognize and reward the hard work the team is putting in, it does not need to be anything fancy it can just things like getting everyone chilled drinks after the end of shift or cooking the dinner. Most importantly you as the leader need to be on the floor with them and putting in in the hours.