A durable power of attorney is a power of attorney by which a principal designates another as the principal’s attorney in fact in writing and the writing contains the words “This power of attorney is not affected by subsequent disability or incapacity of the principal or by lapse of time,” or “This power of attorney becomes effective upon the disability or incapacity of the principal,” or similar words showing the intent of the principal that the authority conferred is exercisable notwithstanding the principal’s subsequent disability or incapacity, and, unless it states a time of termination, notwithstanding the lapse of time since the execution of the instrument.