Do breast lifting excercises really help?

My breasts are in pretty bad shape. I'm only 18 years old, never been pregnant or anything but my breasts are extremely saggy, mostly due to the fact that i for some stupid reason went 6 months without wearing a bra one time, and also due to yoyo dieting, and their size (40 DD) and not wearing the right bra size... I dont have the kind of cash for a breast lift and dont live in the united states so insurance wont cover that. I just went out today and got fitted and bought the right sized bras, so i know thats step one. I also know that moisturizing them helps, but i wanted to know if those breast lifting exercises really will help a lot or not? especially for someone with large breasts?