"On the God Within Us"http://www.stoics.com/seneca_epistles_book_1.html#‘XLI1
"On the Healing Power of the Mind"
"On the Healing Power of the Mind": The prominent theme of this essay is the use of positive thinking to overcome physical illness. A milder theme of the essay is death and how one should look at death. The themes relate to the dichotomy of control and fatalism, respectively.
The former relates in that one cannot control illness, or more specifically it is a thing of which we have some but not complete control. One can do things to hopefully stay healthy (eat well, exercise, proper hygiene, etc.) but for the most part we cannot control physical illness as it is an occurrence of nature. But what we can control in the situation is our mental state. If an ailed man sets the mental goal that he can overcome the illness, and thinks positively that others have faced similar hardship, along with focusing on positive memories, then he gains some control. Though positive thinking cannot guarantee a return to health, it will keep his spirits high and provide him with strength, in a sense.
The topic of death relates to fatalism in that Seneca tells us that death is inevitable. To quote, "you will die, not because you are ill, but because you are alive; even when you have been cured, the same end awaits you; when you have recovered, it will be not death, but ill-health that you have escaped." We are all merely actors, as Epictetus said. We are playing a role and the final scene is death. Death, however, can relate to the dichotomy of control as well due to that fact that we cannot control it. If death occurs naturally, that is, not by suicide, murder, or some form of assistance, then we cannot know its place and time. It is completely out of our hands.
"On the God Within Us": I couldn't make any strong connections between the techniques and this section. The title very much explains the topic. The essay has an Eastern religion vibe, but there are also references to Western conception of god as well. The essay conflates these two viewpoints, but does positively so that we see the importance of the god that dwells within, and also the god that dwells within nature.