People want results without hard work. If you want it bad enough (once you know the way), you will get after it. The sad thing is results come surprisingly quickly and are addictive. The first steps are admittedly the hardest. But you have to make them.
In the end, I really think most people just BELIEVE that once you cross 35 or get married or have kids, that you are supposed to be fat.
Complication makes it easy to explain failure.