“Were you called when a slave? Do not let it worry you; but if you can also become free, rather seize the opportunity.” (1 Corinthians 7:21) 

I like this. Improve your circumstances if you have opportunity, but if not, don’t worry about it; it is not the overriding issue, because: “anyone in [the] Lord that was called when a slave is the Lord’s freedman; likewise he that was called when a freeman is a slave of Christ. You were bought with a price; stop becoming slaves of men” 

as though THEIR arrangements were the meaningful ones. 

Seldom is there slavery today—it is illegal, but there are plenty of circumstances of economic slavery that are very hard on people. The verse is actually no more than the ‘Serenity prayer’ about changing what one can, accepting what one can’t, and being smart enough to know the difference. 

Perhaps it is even the inspiration for it.

More Corinthians here