I haven’t read a ton of Peter Drucker’s writing, I admit. This is a weakness in my continuous learning, because the man was brilliant about management. 
I have just now run across his book, Managing Non-profits, which no doubt many (especially current leaders) have read but I had no idea existed.
First, it’s helpful because Drucker was evidently a believer. This matters because the book is written for non profits including (by intention) churches and missions. It does not require a stretch to apply it.
It’s also helpful because he believes the mission must be managed and this is not a bad thing. But he knows from the start that non profits can’t be measured in the same way as businesses.
Still he reminds us what we do matters and encourages us with the value of our work. He calls us to excellence and does so practically. 
I’m going to read the whole thing. If you are a young leader in a mission(or executive of a small mission) I recommend you check it out.