The link above provides a more detailed explanation of the history and practice of Musar. But one key element is the identification of separate (although often inter-dependent) character traits that one can examine over time, through study with others, and with self-observation and journaling as one takes a designated period of time (usually at least a month) to become aware of how this particular characteristic reveals itself in your own life. You might be looking at the trait of judgment. Or trust. Or, perhaps, compassion.
In Musar, there is a recognition that there is not one right way to exercise each of these traits. The practice is one of paying attention to how it manifests in your own life now in comparison to how you might believe it should manifest if you were able to raise your spiritual life to a higher level. As part of the practice, one of the most important elements of one's self-awareness is to recognize the 'Bechirah' - the choosing points when examining how a particular trait exhibits itself in your life.
So, for example, there may be many kinds of interactions where I feel good about my ability to be non-judgmental. But that is not where I need to do my deepest spiritual work. It is the kinds of interactions where I hear the judgmental voice in me rising sharply... if I can notice what specifically flips that switch in me, I can then begin to really examine and understand where my judgment comes from. The goal is not to arrive at a completely relativist world where I never judge anyone or anything. But perhaps I realize that I can sometimes be harsh. Or sometimes I rule out people or options too quickly when they deserved deeper consideration. And so, over time, I can choose to work on rebalancing this particular soul trait in my own life. And how that looks for me, may be different to how it looks to you. You may be someone who seldom judges. And this may manifest in ways that sometimes has people taking advantage of you and manipulating you. Your soul trait work on this trait may see you rebalancing in a different direction, and becoming a little more judgmental in certain contexts.
When we talk of Elul as a month to take stock, to turn, to reflect.... its not just about counting up 'sins' and telling ourselves that we'll try and do better next year. There are many spiritual practices and tools that we can draw upon from the well of Jewish wisdom. They can guide us in a deeper way so that, when we return to Rosh Hashanah a year from now, we may notice that we've not just circled a year, but that we've spiraled a year, and we've ended up a little higher along the path than the year before.
Rabbi Rachel Gurevitz