When making goals for yourself always be honest and realistic. Remember this will take time, effort and hard work and you must be prepared mentally as well in order to succeed. You will need committment, dedication and accountability. Also be prepared to be discipline, not to mention perseverance as well. In all fairness if you are not prepared to handle all of the above elements then don't start! If you are going to be "wishy washy" with all kinds of excuses to why you didn't eat what you were supposed to eat or why you didn't do cardio or why you can't work out then you have to admit that you are not ready for the task at hand. No problem, come again when you are ready.
You just don't want to do this with a "trying" effort. Because you will be very successful and do exactly what you set out to do...TRY!
NOXQSEZ! Be ready to conquer your goals!