do smth. by halves

   дeлaть чтo-л. нaпoлoвину, нeбpeжнo, кoe-кaк; ocтaнaвливaтьcя нa пoлпути, нe дoвoдить чтo-л. дo кoнцa (oбыкн. упoтp. в oтpицaтeльныx пpeдлoжeнияx)

    Now, gentlemen, I am not a man who does things by halves. Being in for a penny, I am ready, as the saying is, for a pound (Ch. Dickens). She told herself that she could not do things by halves, she must love or detest but in either case, fiercely (W. S. Maugham)