Get All Gauges To 100% And Make Sure You Have No Afflictions, On Day 20 Or Later.
(Yes Cold And Improper Clothing Count As Inflictions)
However, This Achievement Is Linked To The Achievement "Vegetarian".
- So If You Get Vegetarian, It Awards You This One As Well.
I Did Try To Do This In The Main Campaign, But It Wouldn't Unlock.
- So I Assume It's Only Able To Be Done In Endless Mode. (Or At Least, Not On Easy In The Story Mode)
- When The Game Gave It To Me, I Was Not At 100% On Any Gauges, But Again, It's Linked To The Vegetarian Achievement, So When I Got That One, This One Popped Too.
Good Luck!