Dear Joice,
Motivation is an inherent factor and hence it's driven by an individual's own conditioning. An organization can always create the means and the tools for a person to be motivated. You may want to do the following:
1) Establish what the motivating factors are for your managers (through surveys, interviews, one-on-ones, skips, etc.).
2) Create provisions for those factors.
3) Check back with the managers.
4) Review their performance.
Contrary to belief, money is not the biggest motivator, but aspects such as recognition, belongingness, appreciation, completion of work, respect, security, success, availability of resources, freedom to experiment, freedom to make mistakes, feedback, opportunity to learn and share, hospitality, empowerment, etc.
If you can elaborate on your need a little bit more, then I will be in a better position to help you.
Regards,
Kenneth Lewis
09004038788
P.S: I am attaching a document that might help you start the process!