Your stewardship is the process in which a person develops, creates, strengthens, or grows, something like a business, a product, or even your life. Basically you are the captain of the ship and in charge, basically managing and being responsible.
Your mission in life would be the ultimate goal and not the process like the stewardship.
For example, I want to become a doctor, my mission is "how do I become a doctor", my stewardship would be the process leading up to becoming a doctor, like the steps you take to complete your mission.
I hope that clears it up if you need more information let me know.
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