What is the Best Way to Lose Around 40lbs Fast? Please Help!?

I'm 21 years old, 5' 5", and I weigh around 165 lbs which is not normal for me at all. With a change in jobs, lots of stress, several relationships with a swing of weight up and down, I went from weighing a normal weight for me of 130 lbs to 165lbs. This is the heaviest I've ever been in my entire life. I have a gym membership in which I used to go to four times a week. I have a full time 3rd shift job now at an emergency hospital for animals. So I am on my feet for 10 hrs at a time. I've tried dieting, and almost everything you can imagine. I need some serious advise to lose this amount of weight in the fastest healthiest way possible. I can't find the motivation to go to the gym after working my *** off for 10 hrs and then going to the gym to work it off even more. I need nutritional advice and work out advice. Even if it extreme. I need to know how to keep myself motivated to reach my goal. I am getting married this year, so this is my biggest motivation right now. What worked best for you? Did you get a personal trainer? Did you work out by yourself or with a friend? How fast did the weight come off? How did you stick to your goal?

just dont eat sugar and fried things . i am also doing this