Gravity of the situation demands that you lose weight. Being overweight or obese can lead to many problems but one and it is always better to be aware of these problems. From high cholesterol to high blood pressure, a lot of things can turn out to be outcomes of excess weight. Once you are aware of these, you might get motivated to reduce your weight as soon as possible. Working out also helps in making your body stronger than before and you feel refreshed all the time.
People close to you also play a very important role when it comes to motivating someone to lose weight. Imagine tomorrow your boyfriend or girlfriend comes up to you and says you've lost some weight and look great. Wouldn't you keep at it? A little bit of appreciation is all it takes at times. Similarly, a partner at the gym is also a great idea. Working out together is fun. You can also go swimming and cycling together. You can motivate each other especially when there are signs of slowing down or deviating from the path chosen.