We all want contentment in this world! Allah tells us “verily in the remembrance of Allah do hearts find rest”. This world is not our abode of happiness. Allah tells us that we struggle and struggle until we get old.
Happiness are those few moments in-between, like a gasp of fresh air. Imagine if we were happy all the time? We would be miserable. This is why Allah reminds us that with his remembrance we find settlement, not being disturbed.
This is why the Prophet (pbuh) despite suffering hardship after hardship – he was most at peace subhanAllah!