If you enter a race and run half of the route, or even three quarters, then quit, you win nothing.  Starting is important, of course, but so is finishing.  If you hired someone to build you a house, and he built the basement and the frame, then quit, you wouldn't be very happy.  
    This is also true for spiritual development.  Many people start on the right path, but give up after a year or two.  Unfortunately, that means they get little or no benefit from their effort since any gains they made will be quickly lost.  What's more, they will probably look for reasons to justify quitting and Satan will be happy to provide them: "You weren't really getting anything from it", "It's all a waste of time", "Your better off using that time to make more money", etc.  This is understandable because it's just human nature to become excited and enthusiastic about something new, then slowly that enthusiasm fades.  So here are  some suggestions to help keep that from happening:

• When you first start on a spiritual path, and are still full of enthusiasm, write down your reasons for being on that path and why you think it's important and with your time and effort.  Then, when your enthusiasm starts to fade, you can check what to wrote to help get it back
• Whenever you make some significant progress in your spiritual development, even if it's some simple psychic thing like being able to call your dog or cat mentally and they come, write that down as well and refer to it when you are having doubts and your enthusiasm is fading
• Of course, the most important method of all is to have a good spiritual school or spiritual teacher to keep pushing you the way a coach keeps pushing his athletes to perform.