one-track mind

(noun) a mind that is only focused on one topic

Example Sentences:

I have a one-track mind when it comes to shopping. It’s all I can think about!

When I was younger, I had a one-track mind about sports. Now I have a one-track mind about women!

Similar idioms:

1. lose track of
2. lose track of time
3. have something on one’s mind
4. mind-blowing
5. speak one’s mind
6. give someone a piece of your mind
7. blow one’s mind
8. take your mind off