RE: If 'positive thinking' is not advisable - then what approach is? Meet "Non-duality".
There are 2 tools, that can help people on the path to remember their nondual nature.
The first is, to let go the need to know which duality you are - not defining if your thoughts are positive or negative, but most of all, not trying to find out what you are in dual categories. The need to know and define yourself, is inert in the dualistic mind and this can be a worthwhile exercise to let this need to know go.
The second is, what Tim Freke calls "paralogical thinking" - becoming more and more familiar with the notion, that reality (and what you think about it) is always both - positive and negative - and even if for the logical mind it seems as if it can only be the one way and not the other. This can be done by replacing all "OR" statements with "AND". The word "and" works like an antidote to the dualistic mind.
Besides that, light for me is not the opposite of dark. Dark for me means unconscious and it's opposite is conscious/aware. Light has no opposites, since it is already the transcended state. So unconscious light is called darkness and conscious light means Awareness. Light (as in en-light-enment) for me is a description of nondual realization that is nothing and everything at the same time. Cheers and thank you! 🙏
Interesting, but the words will only hold meaning once a person has had the commensurate experience.
For example, there is a conscious darkness, a conscious sleep - it may sound like an oxymoron but the experience is possible, hence then the words no longer sound paradoxical.