sagging of skin is part of aging. You cannot avoid that. Try to see people who are old. Observe them. All you have to do is to accept that fact.

that is good advice above, although I don't think that you have to accept it, if you don't want to. Losing 15lbs by the way, isn't going to make your skin sag. Skin only sags when you lose a large amount of weight. It might if you lost like 50lbs. Especially if you have maintained your weight around the same your whole life. Your skin is probably very elastic, and will probably shrink down a little bit too, right around your new wieght. I know this sounds kind of funny, but have you ever seen that commercial for he little neck/jawline work out tool?You just sit your chin on it and push up and down on it. Well it has little resistant things inside of it that you can set levels on. It really works, my mom's friend has been using one, and I could actually tell a pretty significant difference. It tightens up your jaw line/ neck muscles. It can take years off from your appearance. Seriously, it works, and it doesn't cost much. I think I am going to get one.