Exert your strong points, and the weak points shall perish. (100 sayings by Eiichi Shibusawa)

We can find easily our weaknesses comparing strengths; therefore we tend to focus on overcoming weaknesses. However, if you want to be a professional, we should exert our competence.

When you manage people, we also tend to point out their weaknesses. However, it is better to find their strong points and enhance them, and then they also will be professionals.