Be all in (one's)/the mind American British verb phrase
If you say that something is all in the mind, you mean that it does not real and just exists in your thoughts.
Jane has no symptoms of Covid 19; it's all in his mind.
You have all abilities to finish this examination with flying colors. Your anxiety is all in your mind.
Your dance performance was fantastic! Your fears are all in your mind.
To make a secret plan
To imagine someone or someone being inside of something else
The verb "be" should be conjugated according to its tense.
This cliché meant “in my opinion” from the early 1500s but is heard less often today, and on one’s mind, meaning “occupying one’s thoughts,” dating from the mid-1800s. The current cliché is generally used as a denial of another’s statement, as in "‘I’m sure this woman doesn’t like me.’ ‘No, it’s all in your mind.’”
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.