Your perception of pain mirrors your physical and mental condition.
Sometimes you feel bad, sometimes your pain is livable, sometimes there is no pain at all.
Bad digestion, lack of sleep, stress, ..., even natural events, such as menstruations, are reflected in your daily condition.
External conditions, such as atmospheric pressure, humidity, temperature, ... cause substantial changes in your pain awareness.
Above all, your daily actions and gestures, even while you sleep, challenge your body's aching areas.
Even holding a strange position for just a few minutes may ruin your balance.
Most of the time, the pain level you feel from a particular region remains below your pain threshold.
Then, your actions challenge the equilibrium your body had attained.
You’re in pain.
But, you slowly grow accustomed to the discomfort.
Sooner or later the pain retreats below your threshold.