Archie
It's a great feeling achieving little goals whether weight loss or fitness. I looked at as many mile stones as possible (BMI figures, % targets, seeing a new stone figure on the left hand side etc). I found being in compotition with my siblings good, biggest loser pays the least each week and Christmas we go away for the weekend on the pot of cash. That really helped focus when I know I've got to declare my weight each week.
I think initially the amount of exercise doesn't burn enough calories to make as big an impact as a good diet. What it does do (really well) is change your attitude to your perceived life style, 'I'm a runner not a couch potato'. Also the advances in the early stages are brilliant, from gasping for breath running 30 seconds at the start to running 30 minutes eight or ten weeks later (don't worry how long it takes though).
I would be careful about a lot of conventional advise though. I'm sure that the food and drink industry is to blame for the rise in obesity. I don't have any time for low fat, low calorie or diet foods. There is a lot of evidence that diet pops increase your chances of gaining weight and full fat milk is believed to help you lose weight and it doesn't strip out a lot of the nutrients.
If I have any advise (not that I've quite reached my final goal yet) I'd say don't touch anything processed (even shop bought bread and cartoned OJ). Just have fresh meat, fish, dairy, fruit and veg. Watch the caffeine and don't eat between meals if you can. An old adage but I'm coming round to it actually being right.