3 ideas
A disturbing thought is treated by deliberately producing a competing thought that contradicts it. An anxious prediction is answered by recalling how rarely the feared outcome has actually happened, and a sad thought is answered by recalling that losses are common and can be endured. Because the harmful thought is a mental event, the remedy is also mental: the patient trains themselves to answer their own inner speech instead of simply receiving it.
Sadness has two sources. One kind is a response to a known external event, such as a death or a financial loss, and it is treated by reasoning about that loss. The other kind arises from bodily causes with no clear trigger, and it needs physical remedies alongside counsel. Before treating a low mood, the healer must first work out which kind it is, because the right intervention depends on the cause.
The soul needs regular care just as the body does, and this includes prevention while one is well. A healthy person should prepare calming thoughts ahead of time, the way one keeps medicines at home for a future illness, so that they are ready when fear or grief arrives. Mental disorders count as illnesses in their own right, and each one (anger, fear, sadness, obsession) has its own symptoms and its own treatment.