A promise without consideration is not a contract . . . except in those states where breach of promise is enforceable. Courts have ruled, in that case, there need be no consideration.Something of value given by both parties to a contract that induces them to enter into the agreement to exchange mutual performances.
When you go to your doctor, and he performs a physical, you and he have an implied contract. He will perform the physical; you will pay his reasonable fee. You don't have to sign a formal contract for that to be enforced. When your babysitter watches your kids for three 8-hour days at the $8 an hour rate you promised her . . . and you don't pay her for the third day? You have breached your verbal contract with her.
We'd have pretty complicated lives if verbal contracts were unenforceable.