Part of being prepared is understanding that you cannot be prepared for everything. Have your umbrella in the car for a rainy day, for example, but know you still might get a little wet getting the umbrella out of the trunk, or getting into the car, putting the umbrella away, and closing the door.
In the same way, be prepared when you decide to become healthier. Be prepared to face obstacles when you decide to make any changes. There will always be challenges. When you want to make a change, your body will crave to go back to the old you. It will be easy to make excuses to revert back to bad habits. Be prepared for those feelings to come up. Be prepared to be tempted. Be prepared to have stressful situations tempt you to use them as the reason to give up.
Carry your sense of humor with you. It can be very helpful. Be prepared to have decide to make a different choice regardless.
You have greatness in you. I believe in you!