ἰσχύει [4 verses](3rd sg pres ind act) "It is good" is ischuo, which means "to be strong", "to be powerful", "to prevail", "to be worth," and "to be equivalent to."  - -- The verb translated as "it is good" means "It is strong." The phrase is not from the verb "is" with the adjective "good." This has to be expressed as a verbal phrase because to verb in English means "be strong." This verb means "to be strong in body", "to be powerful," or "to be worth." Christ uses it primarily to mean "strong in body."