You must realize results will not come overnight. This is going to take consistency and dedication. That's why it's more important that you change your lifestyle and not just go on a diet or try some other quick solution. Your goal should be results that are going to last a lifetime and make you a healthier person.
There has to be a much bigger motivating factor behind your transformation than simply just the physical results. You need to have the emotional connection and passion behind your reasons for making that choice to change. When you get to the rough days where you're not seeing a lot of progress and you just feel like nothing is working, that's when the self motivation will carry you through. If you're doing it for the wrong reasons, for somebody else, and not because YOU desire to be healthier and live happier then when the obstacles start to appear you won't have what it takes to get you past them.
This has to be your choice and you have to decide what you are willing to do to get there. Will you make the hard sacrifices like eating better and exercising more? Even when your friends/family are not providing you the support you need and in some case are even creating a negative environment that is not beneficial to reaching your new goals?
Nobody can force you to do this, but nobody can stop you from doing it either! It's in your hands, how badly do you want it?