Losing In Order to Donate Bone Marrow

I've been overweight my whole life, and have tried to lose weight several times-- and it has never lasted more than a few weeks. Over time, I've honestly become very comfortable with myself and my weight. However, lately I have found myself becoming more concerned with my health, rather than my image-- which was the primary focus when I was younger.
In addition, I've recently been interested in signing up for the Bone Marrow National Registry. No specific reason, except for the fact that there are people that go without matches who are desperately ill... and a simple, one time donation can save a life! However, at this time, I am too overweight to donate. I've signed up here in hopes that I can reach my goal weight of 225 lbs, which is the maximum weight requirement to donate for my height of 5'3". I'm in no hurry, but the 85 lbs to lose is daunting. I'm hoping to find some other people for support and to kick some *kitten*!
Is anyone else interested in a challenge such as this? You can check out bethematch.org to find more info. Thanks for the support!