The identity Jean-Luc Picard lived as for an entire lifetime on the dying world of Kataan, experienced through an alien probe in a matter of minutes.
In The Inner Light, an alien probe struck Picard with a beam that rendered him unconscious on the Enterprise-D bridge. In his mind he awoke as Kamin, an iron weaver in the village of Ressik on the planet Kataan. Over decades he married Eline, raised a son and daughter, learned to play the flute and studied the drought that was slowly destroying the planet.
As an old man, Kamin learned the truth: the people of Kataan had known their sun was dying and had launched the probe to preserve the memory of their world in someone who would find it. Picard woke after about 25 minutes, and he kept Kamin's flute, which was found in the probe.