This quote is about personal growth. Most often in life we like to stay in our comfort zone but comfort zones are dangerous. Stepping outside your comfort zone and taking on new challenges can force you to learn, adapt, and develop new abilities. If you challenge yourself, if you push your limits, there are good chances you will unlock new stamina, new skills and new avenues in your behavior that you didn’t even know existed. Always be open to change. Change can unlock personal growth.