"Complaining is refusing to see anything but ourselves." It is a choice to keep something revolving around 'me' and what I want, what suits me the best, what I 'think' is right, etc.
We are told to do ALL things WITHOUT complaining and grumbling. (Phil. 4:13) All of Phil. 4 and Eph. 5 talk about 'walking in love' and as 'lights.' Complaining keeps one from both of these.
The opposite of complaining is GRATITUDE. WOW! How can we be grateful in the midst of a terrible situation? Only by continuing to 'put my mind on things above,' 'by 'looking to Jesus, the Author and Finisher of my faith.' By believing in the Sovereignty of God - that He will 'work ALL things together for good to them who love God.' (Rom. 8:28) - By believing that He engineers all circumstances for his Glory. So - do I want His will and Glory?
I also KNOW that I have 'human responsibility' in this world. and that we live in a 'fallen world.'
God is not the author of evil.

So - just HOW can I be grateful, how do I develop and attitude of gratitude?
Gratitude takes the focus off of self, and presupposes a GIVER - God.
Gratitude is a CHOICE. Do/will I 'choose' (one part of human responsibility) to trust God - that He can work 'this' out for His glory and will?

"Praise God from whom all blessings flow, praise Him all creatures here below. Praise Him above ye heavenly hosts. Praise Father, Son and Holy Ghost."

Remember the Israelites in the wilderness. God had blessed, was blessing - even though it was hard. But they could not SEE what He was doing and complained and asked to go back into slavery. Hind sight is so clear.

His goal is always the same - to fit us for Heaven and bring others to Himself. All will work for those things always.
When we give thanks, there is no room for grumbling and/or complaining about what we lack or envy to or from others. It makes the heart be at peace and frees it with gladness which results in spilling out to others with acts of kindness and generosity.

1 Thess. 5:18; Phil. 4:6,7; Rev. 7:12; Job1:21; Hebrews 13:15,16.