The path to weight loss and fitness gains is relatively easy. ...it's the discipline to stay on the path that's hard.
You need three tools:
1) a cardio plan
2) a heart rate monitor
3) a caloric intake log
Once you figure out your own personal metabolic rate and how many calories you need per day to maintain, gain or lose weight, then it's a matter of math.
For me, the tools I use recently are "Ride Your way Lean" (a cycling plan in a book by SELENE Yeager). I found that cycling is a means of exercise that I can do on a consistent basis and not beat up my joints and ligaments. I've done both P90X and Insanity. They're excellent. They work, but physically they take a toll on your body that makes maintenance difficult. But more important than any PARTICULAR plan is that you HAVE a plan that you can stick with.
I also use a Polar HR monitor that gives me calories burned, % of fat calories, average HR and other key info.
Finally, I use an app called "Lose It" on my phone to quickly log everything I eat. In addition, the "Lose It" app, after giving it a bit of info about your weight loss, gain or maintenance goals will give you a daily caloric "budget" to meet that goal by whatever date you requested (within healthy reason of course). It has a HUGE data base of restaurant, grocery store and brand name foods caloric and nutrition data already within its data base. Oftentimes, instead of entering data for unknown foods, it allows you to simply scan the foods barcode with your phone's camera and all the particulars pop right up.
anyway. I can almost guarantee you that if you use those tools and stick with it, you will DEFINITELY meet your goals.