It is important that you prepare for your operation as soon as you know that you are having one. On the day of the operation you should be in good health. It is important to try and achieve your ideal body weight, as obesity is associated with more complications during surgery. In an ideal world you should not be smoking, do regular exercise, eat sensibly and be taking all prescribed medication. If you have an upper respiratory tract infection it is best to delay the operation. However, some operations cannot be delayed.