I found these observations from Michael McKinley to be encouraging:
David Powlison uses a very helpful illustration about sanctification. He says (and here I am not quoting the words exactly):
The pattern of our life and growth is like a yo-yo. Up and down, up and down.
Pretty depressing, huh? But he continues:
The pattern of our life and growth is like a yo-yo… in the hands of a man walking up a flight of stairs.
I tell you, that one insight has been very helpful to me both in my own life and also in my counseling of others. So often we are so acutely aware of the yo-yo feeling, the ups and downs of our growth and holiness, that we miss the larger picture of growth and maturity that God is graciously working in us.
So a man might still struggle with bursts of anger (up and down, up and down), but if he finds that as he grows in Christ he is more loving, that the outbursts of anger are more rare, less violent, shorter in duration, and that he is quicker to repent and seek reconciliation… there is real upward progress.
This is one of the reasons that we need other Christians in our lives. We need people who can draw our attention to the larger upward pattern of God’s work when we can only see the yo-yo.