A couple of years ago, I was able to sit still and focus on my breathing, for upto 30 minutes at a stretch, and those days I felt more at peace with myself. It was like internal 'world peace' and harmony. Of late I haven't been able to sit still for longer than 15 minutes even when I try, but that may have a lot to do with the fact that I am in college, and constantly juggling n number of things.
These are some previous discussions that you might find useful: