Exposition:
Young people seem to be the most easily distracted group on earth because they are usually met by diverse enticements of gratification. This is why self-discipline, the best virtue for achieving your goals,
should never be underestimated. To say that you are disciplined in terms of achieving your goals means you can bring under control your immediate desires to fulfil higher and more meaningful goals.
From our Scripture reading, we see Apostle Paul comparing his goal of not being disqualified after preaching the gospel to an athlete. He explains that every runner runs intending to obtain a prize. That is the ultimate goal of every runner, so he disciplines himself and restricts himself in all things. Likewise, he, Apostle Paul, punishes himself so that he would not be disqualified after preaching the word of God.
Self-discipline requires self-control, endurance, perseverance, consistency and hard work. Going through these will help you gain mastery over your emotions and withstand the enticement of short-term indulgences. Being self-disciplined will help you to be committed to your plans and ultimately help you courageously achieve your goals.