How did Elrond become immortal?

Could you please elaborate on the circumstances surrounding Elrond's attainment of immortality? I'm curious to know what specific events or actions led to this remarkable transformation. Was it a gift from the gods? A result of his own profound wisdom or bravery? Or perhaps a combination of both? Understanding how Elrond achieved immortality would greatly enrich my knowledge of this fascinating character and his place within the larger narrative.