[Alan Anderson]

Do it in two parts. The first part is to read the button, and whenever the button is pressed set a value to be one second in the future. Leave the value alone when the button is not pressed. The second part is to compare the current time to that value, turn on the motor whenever the value is in the future, and turn off the motor whenever the value is in the past.

I figure you'll have some specific questions to ask now. I'm willing to give specific answers to them. Ask away!