Answer:
The overall message of the poem "To a Mouse" is that we should focus on the present and not so much on the future.
Step-by-step explanation:
When we read the speaker talking, we can see how his encounter with a mouse goes by. He thinks the mouse takes the lead just because of worrying about the present and not the future.
The poem also shows how to plan something for the future, however well it is planned it can go wrong.
In simple words, the narrator lives stressed and frustrated thinking about future plans, and the mouse lives peacefully in the present without so many worries.