Aww, don't think of it like that, if I get to my recommended weight for my height that'll be 9stones down from my highest (started at 17.8 and should be 8.8) but you have to look at it in manageable chunks. I know everyone says that and it seems impossible when all you can think about is the whole 10 stones, but it's really true.
I look at it like this, a week into the Diet Chef the painful heartburn I was having constantly from eating so much stopped. Once I get under 16st (7lbs to go!) my ankle and foot pain stops, once I get under 15.8 I'll weigh less than I did last time I saw the in-laws especially my weight obsessed MIL! (and I'll be seeing them again at New Year!).
After that there's weights I haven't seen in years, after 14st I'll be thinner than I've ever been while being with my partner, after 13st I have dresses in my wardrobe to wear again! (I live in jeans and tops at the moment)...
OK, enough about my plan, you shoudl do your own, what will each half a stone or stone mean for you and how will it change things? That might be as simple as 'after the first half stone I'll have cleared out my system and I'll get less cravings'.
Good luck and you can do it! I don't really believe that I can do it but I keep telling myself every day that noone else can do it for me!