“For it is written, “Rejoice, you childless woman, who cannot give birth to any children! Break into song and shout, you who feel no pains of childbirth! For the children of the deserted woman are more numerous than the children of the woman who has a husband.””  
Galatians 4:27

The latter part of the main verse could only have been found in the awesome book that is the word of God!
He describes an astounding miracle, the woman who had been deserted have more numerous children than the woman who has a husband!
Joy and its expression is that extra resource that would cause an ‘overwhelming abundance’ where it was thought impossible to see ‘few’.
“How that in a great trial of affliction the abundance of their joy and their deep poverty abounded unto the riches of their liberality.”  2 Corinthians 8:2
He explains an equation, he said the Macedonians had a great trial of affliction, in that trial they had two resources- the abundance of their joy AND their deep poverty (so poor, it had depth!), but the wonder is what those two resources produced: the riches of their liberality; what caused poverty to become rich liberality? Joy!
No wonder Paul started the chapter this way:
“Beloved ones, we must tell you about the grace God poured out upon the churches of Macedonia.”  2 Corinthians 8:1, BBE
Jesus said:
“For I say unto you, That unto every one which hath shall be given; and from him that hath not, even that he hath shall be taken away from him.”  Luke 19:26
The one who seemed like he had nothing, when he started to rejoice in thanksgiving, he made available that extra resource that he needed for more to be given unto him.
With all these divine insight and information, if you aren’t rejoicing right now, you should!