I had the same deal. I said when I reached 100kg I'd do something about. The choice was give up beer or start exercising. After thinking about it long and hard, I started running when I hit 103. Been running for a few weeks. It's pretty ugly, but I've finally got to 5km without stopping. Now I weigh in at 99kg, I can stop worrying about it. Back to being a slouch.
But seriously, my goal weight is your fat weight.