I've tried just about everything you can imagine to stay in shape and lose weight. By far, some of the most effective tools I've come across (especially getting ready for my wedding) are my phone aps.
MyFitnessPal is absolutely genius! It helps you track calories and exercise, and totally holds you accountable.
Another ap I love: Map My Run. It's cool because it tracks your run or walk and keeps a record of your times and distances so you can monitor your progress.
There are SO many more out there. Some that will even write a work out or diet plan for you (pretty handy if you ask me)
The site gives a description and rating for each. It's a fantastic resource to find specific aps that will work for your needs!