Go with a Small Plate or Container
There is vast scientific evidence leading to the conclusion that the larger the container from which we eat, the larger portions we tend to eat, so it is an excellent idea to avoid eating from very large plates and instead opt for a smaller plate or container.
Avoid Fast Food Marketing Pull
To prevent temptation try to avoid driving through fast food restaurants in your commute.
Likewise, avoid walking by vending machines and/or not bring change to work. We are preprogrammed by years and years of TV commercials and graphic exposure to crave unhealthy foods, especially those extremely sweet candies offered by vending machines at work.
Eat in Advance of Tempting Area
Eat before going to places where you may be confronted with unhealthy food such as, airports, movie theaters, sporting events, and of course your local Rib Fest or Corn Fest. 
Weighted Vest
If you can pull-off wearing a weighted vest in the office or wherever your job is you may be able to burn extra calories by just doing your usual routines. There are some very slim weighted vests out in the market and they are washable.
Implement a Low Glycemic diet, Low Carb or Slow Carb diet
Enlist the help of a nutritionist or a doctor and ask about going into a diet that would meet your particular nutritional needs and stick to it. The hardest part of any diet is the implementation, so be cognizant of the fact that the diet needs to also fit into your lifestyle. The Low Glycemic diet and the Slow Carb diet are producing lots of good results to a lot of people and are becoming very popular.
Stay Positive and Give Yourself Healthy Rewards for a Job Well Done
When you do achieve your result, make sure you give yourself a pat on the back, be it by giving yourself an hour to just relax and walk at the park, go to the movies, play guitar, or any other pleasurable activity that is healthy and rewarding to you (not to someone else).
Do not Give Yourself Rewards if You Failed
Try not giving yourself rewards when you don’t accomplish the target behavior. If you didn’t make it to the gym today, don’t give yourself the reward that you had predetermined. You don’t want to reinforce lack of behavior, or worse, the occurrence of a different behavior. Make sure you try again tomorrow and do reward yourself when you finally do make it to the gym.
Enroll in Local 5K Races
Paying in advance to attend an event is a strong motivator to actually prepare and perform under the pressure of your social environment. Make sure you tell your friends on Facebook about your race!!! Also, seeing your race results posted on the race sponsor’s website will give you the extra motivation you need going into the next race. You will see images of yourself as a sort of Usain Bolt, racing to the finish line. Trust me, this is a powerful motivator and will keep you accountable to yourself for your own performance in the next race.
You may also want check out ideas on how to get a cheap gym membership so you can stay fit through the Winter months, or more simple ideas on implementing weight loss programs.