While the things we experience through the body are temporary and will inevitably die just as the flesh dies, that part of you that is the image of God is not killed when the body dies. If you really understand that you are eternal, essentially indestructible, you will also understand that nothing can touch you and there is no reason to worry, get upset or grieve about what happens in this world.  Furthermore, you will find no reason to waiver in your resolve to do good things, since it is inevitable that there will be difficulties and equally inevitable that they will pass away.  Your indwelling spirit is invulnerable to the vicissitudes of life.