It seems daunting at first, but my favorite illustration from the Dr Phil book is about point of view..regarding the story of David and Goliath...

When the soldiers saw Goliath their reaction was "He's so big that we can never slay him!"

When David saw Goliath, he said to himself "He's so big that I cannot MISS him"

No matter what plan you choose, you can do it! It's not easy (although, personally, Atkins is easier than any other plan I've tried..but nothing is "magic"..)
But if you keep going, determination can pay off! It's taken me about two years to get down 80 lbs, but I feel better, my health is improved, I was able to quit smoking without gaining all the weight back, and all in all I feel pretty proud of myself...