how can one impact people to be motivated at work and increase productivity?

You could have a highly trained customer service, but still you'd have some buyers who just weren't happy

A good leader at work is always a source of motivation a leader motivates his team by leading by example being very open to team identifying each team members attitude and perspective giving them a pat on back and making them to believe that he/she is second to none and sharing success and failure with them.

 

Positivity, feedback, sense of autonomy and some humor as a cherry on the top!

from my opinion the below may contribute to achieving your goal:1.
Creating a harmonized environment for your employees by: A.
Carefully selecting them to be within the same standard/culture B.
Mind the age difference not to have a huge gap to enhance communication2.
Being Open to them, and close3.
Ask them to contribute in some decisions and provide their own way of solving issues tackling their team performance and output.4.
Recognition (even with a thank you, or any other small prize that means more than it values.) Thats on top of my mind now ,...
if anything came up will let you know :)

Linking appraisal and bonus with productivity is a successful policy  to increase productivity, nevertheless for every rule there are exceptions.

Moreover, a proper business evironment and human relations are important factors of HR motivation and apparently productivity.

First motivation of employee is the working environment, therefore provide good relation, clear understanding on the role, positive feedback and good communication. Motivation as well comes from your own which is willingness to accept and be open.