The lasting motivation does not come from thinking of a skinny body, it comes from thinking about your diet. Do you really want to eat this junk? Just clean up your diet one day at a time. Start making better choices and start doing regular exercise. Don’t aim for perfection. You may think – well then why bother if I am not going to lose 50 lbs this month and start looking like I’m 25 again – well you can have an awesome body and feel great, but depending on how far you have to go, it isn’t going to happen this month. So DON’T PRESSURE YOURSELF. Just start drinking water, stop eating junk, learn when you have had enough and don’t overeat. This isn’t about calorie restriction, just eat normal food in normal portion sizes. Then add a few days of exercise a week and you have it.
A note on exercise: if you are not in the habit of exercising, you should just do something simple like start walking on the treadmill or outside. Maybe do the elliptical for 20 min at a pace that feels comfortable, and then some stretches. You can always do more once you see what you are capable of, but we don’t want you burning out and quitting. Make yourself feel good by accomplishing something, just go to the gym or do a DVD.
I recommend the 21 Day Fix program, this will give you diet and fitness options and they are easy to follow.