Unless you have medical issues such as metabolic and endocrinological illness that is at the root of your obesity, it is your eating pattern that has given you weight issues. Which means, you will have to change your relationship with food -- eat to live, not live to eat-- to achieve success with the surgery. It is not the immediate weight loss that takes place after the surgery, but in the maintenance phase once you have achieved goal, that you have to make sure you do not go back to your old patterns, and as the days progress post op, and you are able to eat more, is when you have to consciously deal with how and what to eat.
Personally, reading/hearing what all the post ops say, I get the feeling that the waiting you have to patiently endure helps in putting you in the mindset to deal with the necessary changes. If eveything went through in the wink of an eye, would you be as mentally prepared for the changes that you have to endure, and the changes you need to make?