A mind that develops love for God will automatically focus on God, you will not need to make an effort to concentrate your mind. One example of this is the Gopis who could not forget Lord Krishna at any moment.
Love is that in which you cannot forget your lover. In fact, you will struggle to forget your lover. Have you seen how a businessman concentrates when trying to balance his/her business accounts? He/ she forgets everything.
Let us see this via a story of Sant Dadu Dayal.