What made me lose weight

I have always been overweight my whole life. One day I just woke up and decided it was time to change. I started with altering my diet and concentrating solely on that and lost 20kgs within the year.. I then started exercising and lost a further 10kgs. I have now put on another 4kg of muscle mass. My next fitness goal is to tone some problems areas of mine including lower stomach, inner thighs, unwanted back fat and my flabby arms.

The first photo in the image was taken in January 2013 at my heaviest.. 91kg. The second photo was taken in September 2016 at 64kg.