What does this quote mean “Recognition of the necessity of hard work and persistence is age-old and universal. Nevertheless, individuals differ dramatically in their stamina for long-term goals....

What does this quote mean “Recognition of the necessity of hard work and persistence is age-old and universal. Nevertheless, individuals differ dramatically in their stamina for long-term goals. Gritty individuals are tortoise-like, distinguished by their propensity to maintain "effort and interest over years despite failure, adversity, and plateaus in progress" (Duckworth, Peterson, Matthews, & Kelly, 2007, p. 1088). Less gritty individuals are, in contrast, more easily discouraged, prone to take "naps" mid-course, and frequently led off track by new passions”