"Strength and growth" encompass both physical and mental advancement. The phrase suggests that becoming stronger and more capable, as well as achieving personal growth, require ongoing dedication.
"Come only through continuous effort" emphasizes that meaningful progress isn't achieved through sporadic actions but through sustained commitment. The word "continuous" underscores the importance of consistency, underscoring that lasting improvement demands persistent and diligent work.
In essence, this statement underscores the necessity of consistent hard work in attaining both inner and outer development. It reinforces the idea that personal transformation is a journey requiring ongoing effort and dedication.