Not too sure how helpful my story will be, but I will tell you anyway.
I was in really great shape when I was in high school and up until about 22. I started having some health issues, which later turned out to be a rare blood disorder. I then discovered that I had a heart problem, so my activity slowed down greatly. For years I didnt do much, activity wise. I still ate well, but ended up gaining a good 30 pounds or so over the course of several years. My doctors finally got me my blood disorder and heart problem under control and I was given the OK to start working out if I chose.
I am 30 now, but didnt start working out again until about 8 months ago. For the first month I kept track of what I was eating and my workouts. I only drank water (lots of it), I didnt eat past 7 if possible (and if I did, it was something light) and I made sure my portions were small. I also ate 6 times a day. I started eating lots of protein and watching my carb intake; more-so when it came to bread. Im Italian, so we tend to go overboard on eating bread. lol
I started out riding my bike for 30-45 mins a day for cardio and heavy weights for an hour for 6 days a week; one rest day. I lost 20 pounds that first month. I was 190 when I started and went to 170. I was shocked. I felt so much different, and looked it as well. The second month in, I decided to change it up a little. I started eating more protein and changed up my weight lifting a little. A long with still riding my bike, I decided to do Tae Bo every other day.
For the most part, Ive stuck with that routine and my results have really impressed me. It was hard, but it has been worth it.
Good luck!
Note: Eat healthy, but make sure to workout too. No candy, soda, fast-food etc... and LOTS of water. You can have a "cheat day" every 2 weeks or so, having a meal you are really craving, but dont go over-board. <--- This will make it a little easier. Also, dont over od it on working out. Do what is comfortable for you. And just remember, you will not lose the weight or gain the muscle over-night. It WILL take some time.