[Belegorn]

Elves had greater control over their bodies which were hardier than Men's especially so as time went on.

It is said in Morgoth's Ring that, "in their earlier days death came more readily; for their bodies were less different from the bodies of men, and the command of their spirits over their bodies less complete." [p. 218] The dominance their spirits had over their bodies increased through time and they became a memory held by their spirits, they became deathless.

The Elves seemed to be nevertheless effected by different elements in Arda, like those introduced by Morgoth, such as death absent of violence to their physical bodies, see Míriel.