Walked: 11.3 Km
The Fourth Way as exposed by Ouspensky contains a very simple exercise to notice your progress in meditation: observe the dials on an analog clock (or an image of it on a phone) while repeating "I am [my name]" in your mind. Eventually, your mind will sidetrack and you will begin thinking about something else. Notice how much time has passed. For a beginner, it is rare to make it past the minute mark.
Training in mediation is mainly about training attention. Attention should be placed in a neutral place, which is often the breath or a mantra, but it can also be a candle, the sound of a river, anywhere your attention can rest without any kind of excitement.
The beginner becomes frustrated when they discover that they are incapable of sustaining it for more than a couple of seconds. But frustration is a trap. The first thing one ought to do is to come back to the object of attention without getting caught up in the frustration. It's not unlike a baby stumbling when he's learning to walk. Should babies be frustrated when they fall, they'd soon give up on walking.
Once one has learned to walk, that is, to sustain attention for significant amounts of time, all sorts of inner phenomena reveal themselves. At first it is best not to engage in it, attention must remain at the chosen place, and the phenomena can be observed in the periphery.
When looking at a night sky full of stars, perhaps you may have noticed that you see more stars just outside of your line of sight. When you move your gaze to look at them, they seem to disappear. In meditation the phenomena is similar, you may think you understand what you are experiencing if you put attention on it, but this causes a shift in perspective and you will engage with it in your habitual way of thinking. The objective is to experience, not to understand. Understanding may come after the meditation.
In the beginning the meditative state is elusive, if the objective were to submerge oneself into the state, you would find yourself floating above it and submerging into it at irregular intervals. As more experienced is gained, the submersion becomes deeper and it less prone to be lost by lack of attention.
The submersion brings all kind of layers which are useless to describe in words. When you submerge into new levels of depth you become fascinated with the things you see and may think "this is it!", but there is no "it" except going deeper. What we're aiming here is a state of complete emptiness, reaching profundities where light no longer penetrates into the depths of the ocean of consciousness.
One could say there's a parallel between the mind and the body when it comes to training. When you exercise there's little immediate results to observe, but on the long term the effects are obvious. Unfortunately there's no mirror for the mind, so progress is difficult to gauge. If you are persistent in your regular practice, your mirror will come from other people and events. Events or people which used to negative emotions cease to cause them and you are often surprised at your reaction to them.
This is true of both negative and positive emotions, and though it may sound like anhedonia or detachment from life, it is the other end of the extreme. If the mind were a storm, the depressed mind would numb itself and come into a state of catatonia as to not experience the inner violence. The trained mind would experience it in full without reacting to it. Outwardly the appearnce is the same, inwardly they are opposite.
Listen to no dogma over how and when to meditate. The easiest way to come into the state is by sitting in a comfortable position with your back straight, and is perhaps the best way for beginners. But you can meditate lying down, walking, standing; really any circumstance that does not require your attention to shift.
Guided meditations are a great introduction, but they are a train which follows a fixed track. Ultimately you want to set out into the journey by foot. This allows you to explore the vastness of consciousness at your own pace, and gives freedom for exploring whatever is what you want to know.
Why meditation works is a mystery to which I haven't heard an answer which is not spiritual. The movement of our breath brings us into contact with something greater than us, and our thoughts seem pithy in the scale of this experience. Thus, we cease to believe that we are what we think. A whole range of experience arises when we quiet the mind, experiences which go way beyond the confines of our skull, and the universe is experienced as being part of one's consciousness.