Answer : First of all and most IMPORTANT...you must REALLY DECIDED to do that!!! If the answer is YES again you must follow 2 steps
1...HEALTHY DIET... and this means Fruits and Herbs at most or alternatively I suggest Natural Supplements which they REALLY help you to improve the quality of life by controling some negative levels.
2...EXERCISE...another very important thing but difficult...at least from the start of your way to Success!!!
NO...You can't do that in one week...