Stephen Covey Quotes about Effort
Stephen R. Covey (1994). “Daily Reflections for Highly Effective People: Living THE SEVEN HABITS OF HIGHLY SUCCESSFUL PEOPLE Every Day”, p.159, Simon and Schuster
Stephen R. Covey (2016). “The 7 Habits of Highly Effective People: Powerful Lessons in Personal Change Interactive Edition”, p.57, Mango Media Inc.