We all know that to achieve maximum results we must blend a good diet with a good training regimen. The problem why most people just like yourself fall off isn't because you don't want to really achieve your goal, the problem is a persons discipline. The lack of discipline is why you have not seen the results you want. The lack of discipline is why it seems to be taking so long. Think about it, how many times have you messed up on your diet? How many times have you missed sessions, or had days even time periods (weeks, months) of inactivity after you said you was going to commit to it?
The short cut is discipline, want a better 90 day result get better discipline. Want a better 6 month result than the last 6 months get better discipline.