(idiom) to pursue unrealistic or overly ambitious goals; to bite off more than one can chew.

to pursue or get involved in external matters instead of focusing on one's own duties or business

to be completely focused and free of distractions; concentrated on a single goal

(literary) To let one's attention wander to other things; to be distracted from the task at hand.

to move swiftly; to run fast

To neglect one's primary responsibilities or proper role in favor of outside distractions; to focus on matters outside one's own sphere.