John Kennedy actually said...

"So I hope that you will regard this as the first installment in a long life of service in the most exciting career in the most exciting time."

"I hope that when you come back that we can persuade you to come and serve in the United States Government in other areas."

"The White House belongs to all the people, but I think it particularly belongs to you."

"We are very glad to welcome you here to the White House."