Thanks for getting in touch and for highlighting something which sounds as though it may be causing a number of people some difficulty. Always good to know you’re not alone, right? Funnily enough, I used to really struggle with visualization, too. Not just the dreaded pinprick of light, but every visualization. Sometimes I couldn’t imagine it, sometimes it was upside down, sometimes I’d be lost in thought for ages and more often than not I’d get quite frustrated or depressed at my inability to apply the instructions. There are two parts to the question, so let’s look at them separately. The usual difficulty with this exercise is the attitude toward it, although it sounds like that may not be the case for you personally. By "attitude," I mean expectation, effort, and so on. These are common themes which impact all meditation exercises, but visualization techniques seem to be particularly sensitive to them. The way to avoid this is to approach the visualization in the same way as we might imagine a kind old friend. It doesn’t take any real effort, we simply picture them in our mind and it makes us smile.
And, of course, just as it’s difficult to remain focused on the breath at times, we should fully expect the mind to wander and for this to be a lifelong training in returning our attention back to the visualization when we realize this is happening. So it is quite normal when you are imagining that image getting wider and wider, that you start to remember old friends in different countries or the news report you saw earlier of a festival in one place and a war in another. A way to avoid this tendency is to speed it up a little. So it’s like a wave that goes out in every direction—maybe just three to five seconds for the whole thing. You can then repeat that same visualization. At other times, we may feel as though the mind simply can’t go any bigger. But this is just training. If we think it should go bigger then we are thinking about it, expecting something and projecting our own idea of what it should be rather than what it is. But if we can just accept it as it is in this moment, right now, today, then in time it will naturally change. As we continue to practice, the mind gets bigger, more spacious. It doesn’t matter exactly how big, it is simply being in touch with that feeling of spaciousness, whatever it is on the day. In short, all these techniques take time. There's no need to go back to the beginning and what you are going through is nothing other than learning the technique. If you're anything like most people, some techniques you'll immediately enjoy and feel naturally inclined toward, but others will be very challenging. It's often the latter we learn more from, though, even if we don't enjoy them quite so much, so do stay with it if you can.
Warm wishes, Andy