Definitions: (1) promoting further development or advancement; positive formation; (2) able or helping to erect or create; (3) building up and making better; serving to improve

• You must not under any pretense allow your mind to dwell on any thought that is not positive, constructive, optimistic, or kind.  Emmet Fox (1886–1951) Irish spiritual leader
• You should tell yourself frequently ‘I will only react to constructive suggestions.’ This gives you positive ammunition against your own negative thoughts and those of others. — Dorothy Jane Roberts (1929–1984) American author

What are the foundations upon which to construct a solid personality? A few suggestions: curiosity, High ideals, insight, moral fiber, self-awareness.