It would be one thing to hear "rejoice always" from someone living with plenty but quite another from someone in a challenging situation - Philippians 4:4-5
There is something about being "in the Lord"
If someone is "in the Lord", there is always something bigger than our trials
Paul also had a deep conviction that whatever is one: The Lord Is Near
This is how men and women of God can be joyful and gentle in the most stressful times
God is monitoring their pain not allow more than we can bear and giving his strength
The Lord is near to all who call on him - Psalms 145:18
He is near in every situation we encounter
He is calling on them and us to rejoice always and to have a great attitude