Attention is the fundamental resource of the mind, and meditation is attention training. Focused attention meditation — repeatedly bringing a wandering mind back to a single point of focus — is essentially a workout for the prefrontal cortex, the brain region responsible for sustained attention and working memory. Studies show that even brief meditation training (as little as 4 sessions of 20 minutes) significantly improves performance on tasks requiring sustained attention and working memory. Long-term meditators show structural brain changes in attention-related regions and score significantly higher on measures of focused attention than non-meditators.

Reference:

Wikipedia: Attention

https://en.wikipedia.org/wiki/Attention