To make your meditations more powerful, you can visualize what you want, but what I've read over and over again about the manifestation process is, you have to envision it as already having happened. So, with that in mind, when you meditate on Peace on Earth, Good will to all, (example,) do it as though you are REMEMBERING when it happened. Remember how it felt, how it looked, where you were, what you were doing. Remember how you celebrated, cheered, hugged anyone that was near enough to be hugged... This IS powerful. Try it and see for yourself. The problem with visualization by it self, is that it is nebulous, that is to say, it leaves when it happens or happened in uncertainty. The creative process works in the here now moment by moment unfolding, so remembering you already have what you desire, more powerfully empowers it to manifest in this here now moment by moment unfolding. Even so, this process is like trying to catch a downy feather as it floats to the ground, the more you grab at it, the more it evades your grasp, so instead, just place your hand in line with the path the feather is falling, and be still long enough for it to land in your hand. This is an analogy for how things come to us via the creative process.