This is a very important verse from Shankara. Most people concentrate on the point being made about samadhi when reading this verse, but note how it states that manana is ‘one hundred times’ superior to sravana.
Yesterday in Satsang, we were talking about manana and how we can do this more effectively, and how this naturally will lead to nididhyasana and then samadhi and then full realisation. You will start to find that the motivation to do practice will increase.
Thinking about the teachings, seeing the tricks the ego keeps on playing on you to perpetuate itself, seeing the very nature of the ego for yourself, writing this all down and reflecting upon it means the ego has less room to manoevure. Write down all your thoughts, write down all your insights, get it all on paper.
At this point in the teaching it is helpful to do this as the mind, being very fickle and forgetful will quickly forget the insights you have previously made, thus perpetuating itself.
As you engage with this aspect of the teaching, you will see how just powerful it indeed is, how the ego has less and less room to move in, how the ego weakens naturally, and how peace and love more and more come into you, merging with your very Being.
Namaste 
Tom Das 