be all in somebody's/the mind
be all in (one's)/the mind
To exist solely in one's thoughts, rather than in reality. Don't tell me that my worries are all in my mind—you know this can be a dangerous area. Your presentation sounded great, honestly. Your fears are all in the mind.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
be all in somebody’s/the ˈmindnot be true or real; be imagined: She’s not really ill — it’s all in the mind.
Farlex Partner Idioms Dictionary © Farlex 2017