This is a motivational saying about setting and achieving goals. When you set a goal (begin) it is important to have a clear idea of your goal (end). This will increase the chance of reaching your goal.
For example, "Person A" might say "I should learn Spanish" or "Someday I would like to learn Spanish". These statements are weak to an achiever.
While "Person B" could say:
(Begin) My goal I set today August 9th, 2016:
(End in mind) By August 9th, 2019, I will be conversation fluent in Spanish. I will test out at the C1 level. I will easily be able to have conversations with native speakers. This will allow for new cultural experiences, open my mind to new perspectives and enrich my life. I will be able to travel to places in South America where English is not spoken. I will make new friends in foreign countries. I will be able to converse with my Aunt who only speaks Spanish. Fluency in Spanish will allow me to achieve my dream of living in a foreign country, because I will no longer be intimidated by language barriers.
Which person has a better chance of success? Yep, that's why goal-setting and motivational workshops use the phrase (and concept).