Weight loss & sagging skin

I’ve lost about 50 lbs recently, and I’m planning to lose about 50 more. My biggest concern is that my skin will all be saggy at the end! I have large breasts, and the skin has become looser over the last few months. Now I know that experts say the best thing for saggy skin is exercise and muscle building, but that doesn’t seem like it will actually tighten the skin itself. Is there anything I can do to solve this, or at least lessen the effects?