Why do you need self motivation?
* You cannot always rely on others to encourage you, if you have positive friends who are always there when you need them then you are indeed lucky and very much in the minority. If you are lonely or have few friends when you face any difficulties in your life you must rely on your own motivation to get you through. Lack of self motivation at that time could lead to depression.
* You need self motivation to achieve because if you don't encourage yourself to accept opportunity and challenge who will?
* To plan and find direction in your life
* To take up a new activity, hobby or challenge
* To be enthusiastic about life and living
* To have the courage to see things through despite setbacks or negative comments from others
This is not an exhaustive list because self motivation is so important in every aspect of your life. The very fact that you are here searching for answers and trying to improve yourself shows that you are motivated.