There's no magic bullet. The only way to lose weight is to eat right and exercise.
I've lost 30 pounds over the last 12 months and have had to give up very little. It's not about `giving up', it's about moderating for a small period of time for an end result.
So, with your one Pepsi, you may have to not have one every day for, say, three weeks in order to achieve your goal. It doesn't mean that you can never have one ever again in your life, or even one every day ever again in your life! It just means that while you're trying to lose weight, you shouldn't have one every day. It's not forever.
As soon as I realised that foregoing certain foods is not forever, losing weight became a breeze and also forced me to explore more creative food options. I ended up really enjoying my weight loss, it wasn't a burden and it wasn't a chore, and I learned how to cook some of the most delicious meals I've ever had.
But again, there's no quick fix, or magic formula. You gotta try, and you gotta work at it. Eat less, exercise, and you'll lose the weight easy!