Yes, you can still make your own decisions. The provisions in the advance directive are only applicable once you are diagnosed with a terminal condition or deemed by two physicians to be in a permanent unconscious condition. The only time that an advance directive will take effect is when you cannot make decisions for yourself.
Also, you can change your health care directive at any time. However, be sure to forward a copy of the new health care directive to the health care facility where you will be treated, as well as to your health care proxy and close family.