Sum up your mission in 2 sentences. One for the responsibility, one for the success criteria.
Consider using this type of approach:
1. mission, role, responsibility:
"My mission as a (example: Project Manager) is to make sure that (..., ..., ...)."
11. success criteria, metrics, desired state:
"I know that I'm doing a good job, if I (..., ..., ...)."
!!- remember: choose there criteria within your area of influence!
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Note: If you have more than one role in your job, I suggest doing one mission statement for each role. You might also want to test this out with other types of roles like "mother" or "husband" or "citizen"...
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