After being quite big (after my babies - I lost 4 ish stone). If I ever need to drop a bit of weight, Iam on a "healthy eating thing at the mo, then I just imagine me being in my little size 10 combats and the feel of my clothes being loose, and it spurs me on. If i have that little voice that says "oh go on, one biscuit wont hurt", I ALWAYS listen to the other little voice that says "dont do it". I know that sounds obvious. It REALLY is worth it!
best thing to do is to always be doing something as the main reason people eat is boredom, my x was 28stone and he went down to 11stone on lighter life, he took up lots of hobbies so he wasnt bored and was always doing something, i also suggest putting a picture u dislike on your fridge and cupboards where the nice stuff is