When I saw the title, my first thought was, "With a mirror, duh!" But then I actually read the post.
While it is beneficial to acknowledge our shortcomings, I don't at all find it beneficial to self-flagellate. Part of the greatest commandment is to love our neighbor as ourselves, and I sometimes wonder if a reason why so many Christians are cold or even hostile towards our neighbors is because they don't have any love for themselves, and I don't believe we can truly love others unless we also have love for ourselves.
God proclaimed all of his creation to be good and even very good, and I don't believe that's changed. Sin corrupts but cannot and does not have the power to erase the goodness of God's handiwork.
I don't always feel the above on my worst days, but other days it is much easier to view myself in a much more kind and compassionate way. It is very easy to see our imperfections, our sin, the ways we believe we miss the mark, but it can be a real struggle to see just how greatly we are blessed and how deeply we are loved.