To put it quite simply, there is absolutely no reason to ever stop your diet. Just because you finally made it to your goal weight, does not mean you are going to stay that way for very long. Now is the time you have to go through your entire routine, and decide how much will it take to stay the way you are, or even slightly improve on it. The most beautiful people in the world don’t keep looking like that when they become lazy, they get fat and out of shape like everyone else. Keep as active as possible, if the running was a huge part of you dropping the weight (which usually is), then try your best to keep running almost the same amount as you were before.
Now that you have already dropped the weight you wanted to lose, you may try to adjust your diet in a way as to resume eating some of the foods that you missed. There is no sense in depriving yourself now that you have already lost the weight. Do not allow too many calories back in, but you can afford to add a few since you will still be jogging or running which will burn off most calories before they become fat. You must be careful as to not allow any processed food, but if you miss having your occasional homemade cheeseburger or slice of pizza go for it!
Never lose sight of where you came from. If you keep pictures around of what you looked like before you started your diet, you will be far less likely to become lazy and allow yourself to look this way again. This includes not throwing out any old diaries or journals you may have written, if you had any depression caused by your unhealthy lifestyle it will most likely show through what you wrote. So if you ever start to fall off track and catch yourself gaining 3 pounds, look at a picture and remind yourself how awful you felt with that extra 20-30 pounds you lugged around.
If you can stay this weight up to 6 months, it’s time to really congratulate yourself. Most likely you won’t gain much back especially if you keep running and stay active for the rest of your life. Now go out and find someone else, family or friend, tell them your amazing story and get them excited enough to want to lose weight themselves. If enough people did this imagine how much thinner the world would be!