These are common English expressions. These two phrases means to do what one promises or says. For example, a girl tells a boy that she wants to marry him, but he complains to his friend that she is not consistent with her words. He tells his friend, "She says she wants to marry me, but because she is flirting with other men she is not acting that way." The idiom "live up to it" would be interchangeable: "She says she wants to marry me, but she is not living up to it." Как сказать по-русски?