I need to reduce my weight and I can't do heavy exercises as said by doctor,how can I do this

By reducing your caloric intake, eating natural, low calorie, low sugar, low sodium, low fat foods, like lots of veggies, fruits, beans, legumes, nuts, seeds, lean meats, cutting out sugar, salty snacks, cakes, cookies. And eating low fat, 1-2% or skim milk, lowfat, part skim, skim cheese and lowfat, non fat yogurt. Change from white flour products, to 100% whole grains, like wheat, rice, breads, cereals, and pastas. Watch serving sizes, smaller portions and read nutritional labels if your not sure what one serving/portions size is. If your into soda or presweetened try switching to water or 100% juice. There's are lots of low impact exercises, I'm sure you can do, you should discuss with your Doctor, depending on your medical condition what would be allowable for you and for what time. Just walking for 20 minutes would help, but check with your Doctor to make sure.