STAR WARS: Battlefront Classic Collection

This can be achieved offline playing against bots. You can check how many medals you have at anytime by doing the following. Select profile>Main menu>Options>Career stats. To obtain this achievement you must earn 64 Endurance medals.

Or in other words earn 12 points in a life without dying 64 times.

There are 4 different medal categories

Green: 0-3
Veteran: 4-31
Elite: 32-63
Legendary: 64+

You’ll need to earn the Endurance medal 64 times

You get this medal by scoring 12 points in one life

After earning 32 Endurance medals you'll unlock Elite medal Rank which reduces the requirements to earn Endurance to 9 points in one life.