SamMalone, I can relate to this situation. You make improvements. You change yourself, and your personality for the better. New people you come in contact with like you, as now you're much more of a positive person. Unfortunately though, we all have a tax to pay for making poor choices, even if those choices we made were during our youth when we didn't know any better.
For some that tax could be taking a couple years to get the body you want, which is the price paid for the poor decision of neglecting your health for a decade. In this case, the poor choice made was spending years of your life building a social network that is full of chumps, negative people, and anti-social friends who are life's losers. There is a tax for this choice, unfortunately, and that is the time it will take you to start building a new social network.
Here is the course of action for this challenge. From now on, only spend your time hanging out with people who are positive, who are winners and lift you up. Be legitimately too busy to hang out with people like your old friends who bring you down. I'm not saying cut ties with them completely, but life is too short to waste time with the time-wasters of the world. The younger you're able to step back and make all the corrections you need to make to have the successful life you want to have, the sooner you'll get there. The compound effect of making changes earlier is enormous.
For me personally, the difficult part about rebuilding the social network has been leaving the party. So many of my friendships were based around getting wasted and wasting time. It's funny how people you once considered great friends get so jealous and don't wish to associate with you anymore when they see you getting successful. They have no clue why you wouldn't want to join in their loathing of the world around them. Blows my mind.