#1 congrats on your weight loss. I know this is hard to accept as I still can't accept it. I know what it feels like to be overweight when everyone else around you is skinny. Please focus on the fact that you were able to do it and didn't need to be on a show like "The Biggest Loser". That shows incredible determination.
#2 I'm not sure what your body looks like, but are you sure it's all skin and not flab left over? I went from 285 to 180 without really weight lifting, and if I showed you a picture at that point, it looked like I had loose skin floating around my mid-section. When I started p90x and added muscle while dropping more body fat, that flap on my mid-section tightened up. If you message me, I will show you want I mean.
#3 I recommend P90X if you're not used to weight lifting. I jumped right into it and it changed my life. I learned to lift and focus on muscle groups. I started by purchasing a set of resistant bands from Amazon ($30) and used that for my first round with great results. I completely recommend just going through the weight lifting videos for a couple of weeks to get used to the regimen.
I would do this in the beginning:
Chest/Back - Mon
Ab Ripper X - Tue
Plyometrics - Wed
Shoulder/Biceps/Triceps - Thur
Ab Ripper X - Fri
Kenpo X - Sat
Legs/Back - Sun
Once I got used to doing this, I started following the program 100%. Once you get more fit, you'll be able to do your own crazy Ab Ripper XXX in between sets.
Let me know if you have any questions and good luck! Congrats once again and I know you can do this since you've already lost 140 lbs