When I was working Step Four with my sponsor, he suggested that I pick one particular person, institution, or principle at a time and write up an inventory to share with him specifically about that one person. This was a lot of hard but very good work that resulted in a significant change in how I see myself in relation to others and God.
One of the biggest changes for me was to learn how to practice real honesty with myself and others. Previously, I had a very narrow definition of honesty. As long as I didn't tell an outright lie to someone else, I thought I was being honest. But by working Step Four-- using a far more honest definition of dishonesty (given to me by my sponsor)--I was able to see for the first time how many lies I told others as well as myself. I found that I justified and rationalized pretty much all the time. I would lie to myself so that I could excuse my faults and harms to others and especially my resentments.
Eventually, I learned through that process that any resentment I held onto was a major trigger for my lust, and then the acting out behaviors that followed. Resentment is toxic for me, and I must surrender resentment if I wish to stay free from the bondage it brings. I don't believe I would have learned that truth and made the necessary changes in my life had I not worked the Steps under the direction of my sponsor--because without that work, I would not have experienced a spiritual awakening into right relationship with God and others. Working Step Four made major changes in my life.