About To Break

This achievement is only obtainable while on any of the quests given by Wayne the Ancestral in Stormsong Valley. Once you accept one of his quests you will get Strained and a bar which fills up when you take damage from mobs on the island.

When the bar fills up you will get The Stage is Set, your bar starts to empty itself and you gain one of these effects:
Afraid - permanent debuff
Lost Cause - permanent debuff
Sadistic - permanent debuff
Surging Confidence - 10 minute buff
Empowered - 10 minute buff
Clarity - 10 minute buff
Crushing Dread - 3 second debuff
The order of getting them is random and you will only get the achievement after getting the first three debuffs.

Filling up the strain bar takes a really long time if you don't have any healing spells so it would be good to do it in a healing spec or have someone else heal while the mobs hit you.

In case you have completed the questline, you'll notice that the strain bar doesn't appear anymore - this is a bug that might get fixed in the future. A workaround is to wait for a World Quest to be up such as Iconoclasm.

Once you get the strain bar, you'll want to find 2 [npc=141986] on the shore and let them hit you with [spell=278316] to generate strain. Do not go up the hill, the strain bar will disappear. You can AFK with this method if your class can passively heal.

In case you haven't completed the questline, then you should consider other methods to get the achievement. For example when Warbringer Yenajz is up, his [spell=274932] will fill your strain bar so that's an easy way to speed it up.

If you talk to [npc=133640] while you are still debuffed, you will have the dialog option "I am troubled. Can you help me?" Wayne will tell you to head to an idol on the island but warns you to beware. Head to 76, 50 by going out the door and down the hill on your left. Clicking the Purifying Effigy next to the idol will spawn a mob that's not too hard to kill. When he dies all your debuffs will be removed.