Self motivation is something that does not come easy, it is something that has to be worked on continuously so that it can be fully achieved. Now you can have someone teach you self motivation, or you can step up to the plate and try to achieve it by teaching it to yourself.
The first and possibly most simple thing to do would be to hang around people that are self motivated and like to motivate other people. Within time this will rub off on you in a positive way. This is much better instead of hanging out with people who have a negative attitude towards life.
Try to make a list of everything that motivates you even if you think it is silly because remember this is your own personal list that applies to you. After you have made your list make sure that you put it somewhere that you could easily see it even if you post sticky pads all around your house.
Next learn different ways to become even better. Your list may help you however there could be other ways that could help you achieve your goals and be more motivated even faster. One thing that definitely works is try to teach other people, once you try to help other people become stronger, you yourself will become stronger.
Faith always works so ask god to help you, just because he does not deliver right away it does not mean it is not coming. Just remember that you do not have to waste money on books, tape recordings and other things similar to that which will not necessarily work for you. It is within you and sometimes surprisingly the most simple of all things seem to be the ones that help you the most. So try it out and see what happens.