I once heard John Piper talk about setting up an "income governor" for his family where his disposable income would not affected by the success of his books (or other stuff).  He wanted to limit how much money he would make, so he set up in advance a plan for  a maximum income. I think the point is along the lines of Psalm 30:8b-9:

give me neither poverty nor riches; feed me with the food that is needful for me, lest I be full and deny you and say, “Who is the Lord?” or lest I be poor and steal and profane the name of my God.

I am thinking along the same lines--wouldn't it be great to write down how much income per year is enough? This is my current thinking.  I publish it here as an accountability that if I change my mind, I must either remove this post or modify the underlying numbers: The formula is my personal income should be no more than a generous allowance given a certain family size living in the United States. For "given a certain family size living in the United States", I can use the Federal Poverty Guidelines for each year (which will rely on government numbers of what "the basics" cost to live in the United States). For "a generous allowance" I can multiply the Federal Poverty Guidelines by a certain factor because I'm not trying to live in poverty ("give me neither poverty..."). And I'm choosing to modify the Federal numbers that add the same amount per child to your allowance. The thinking is based on the assumption that going from 0 kids to 1 kids cost the most, 1 kid to 2 kids cost the next most, etc.  Each additional kid adds less to the income allowance than the kid before. Someone please ask me in a year if I'm still enforcing this. (Hint: if I answer "yeah, I'm totally doing fine", it probably means I'm not even making the upper limit so it's not even an issue yet). (What I'm not planning is stop working when I make X amount, but to create a control that diverts the excess earnings into other uses)