What should one do when feeling distressed and unable to endure, despite a person's strength and patience in the face of tribulations?

The worldly life is an abode of trial. Allah tests His servants in it to distinguish the truthful from the liars, and the patient from others. Supplication (Du'a) and patience are among the greatest aids in overcoming trials. There is no harm in complaining to someone who can help one endure a calamity, if it is for a legitimate purpose and not out of exasperation or discontentment.