I can understand your concern.
What your doctor has said is right. You need to lose weight.
Diet and exercise both will be required to lose weight.
Either of them alone wont promise you good results but together, they will be great.
Have a high protein, low carbohydrate, high fiber diet.
Avoid oily foods and foods with high glycemic index.
Have 5 smaller meals in a day rather than having 3 full meals.
Drink lots of water.
Remember, the trick is simple, in order to lose weight you will need to take in less calories than your daily required and burn more calories than what you take in.
Cardio workout will help in burning calories and lots of them.
Running, jogging, doing lunges, playing certain sports like badminton etc are great exercises.
Also do core strengthening excercises, they help in burning a lot of calories.
Consult a dietician for detailed diet chart.
Dr. Anil Kumar Jain