(edit for clarification: I mean the 3rd mental exercise of step 1)
More specifically - what constitutes one pointedness in this exercise? From what I understood, you choose a specific idea or subject and follow the train of thought while dismissing unrelated intruding thoughts.
The more traditional approach to one pointedness is choosing a single point of attention such as a symbol or a mantra and focusing exclusively upon it.
However, focusing exclusively upon a picture(symbol) or sound(mantra) sounds more like the step 2 mental exercise..
The way I did it was taking an interesting subject, let's say the fire element from the theory section. I would then focus on the idea and follow the train of thought and related associations such as seeing fire, particles expand and accelerate from heat, dancing flames consuming what's in their way, light, illumination, will, the fire within, the drive for action, astrological fire characteristics, yang energy, electricity and so on and so forth..
I don't talk in my head or force it, I let the stream of thoughts flow of its own and so there are periods of silence as nothing comes up but I still hold the original idea in my mind. There are of course unrelated thoughts that may appear as I go, and I immediately shun them away and maintain my focus upon the idea.
I also have to discern as I do the exercise which thoughts are related and which are not, which can be confusing. If I'll use the above example of "fire", I might get a picture of a field with the sun shining. I then decide if it's unrelated or maybe the sun is bringing light, heat and expansion causing the flowers to bloom, and yet an elemental imbalance (no humidity, drying the plants, lack of "water" element) can bring out the negative qualities of fire and start a bush fire.
Occasionally I get some interesting associations and insights that way, but as a concentration exercise - I'm not really feeling it. It's very easy for me, and yet the transition from this to VoM doesn't feel very natural..
So even though I feel like this is a useful and entertaining exercise and I don't feel like I've wasted my time doing this, I'm not sure it's the right way in the context of the exercises (especially as preparation for VoM).
Appreciate your opinion!