I recommend reading the link:
https://satanslibrary.org/Rtrs/Raising_Energies.html
State of positive should be natural when you're thinking is in perfect order. To achieve this kind of thinking, you need to train yourself to really assess your problems and in every bad situation be able to find positive and positive moments that will help you fix this situation.
The reason for the lack of positive emotions may also be the lack output of negative when the negative accumulates.
It is also necessary to be able to release your negative emotions.
I recommend that you focus on cleaning your chakras, because removing dirt from your chakras also frees you from negativity and allows you to look at things sensibly and will allow you to feel positive in a natural way.