When you do good things are expecting that you will get the reward for the good things that you already did is just like expecting wild tiger will keep you alive after you help him. The world sometimes can be cruel and will never care about your feelings, about the good deeds that you already do. It might bring some tasty fruit at some other time, but expecting it to happen instantaneously is just a fool's way of thinking.
life is hard, it can crush you if you are weak. You have to be strong to keep on moving and do all the things that you needed to stay alive and to stay survive. It is ok that you will fail and feel tired, because it is such a long journey and it is rather a marathon run than a sprint, all you need to do is to keep going.
The world is cruel because if might throw things that you have never expected, but somehow it was what is serve in front of you. Wheter you lie it or not, but that is the thing that you have to face. And all you have to do is to face those things, rather than running away from it, because running away will only activate another trap that will hinder your journey.
So stay strong, be strong, be brave and face this hard and cruel world, you can make it, we will make it.