My life is a constant cycle between improving mentally/spiritually, and regressing. It seems, everytime I have a low point in my life, I wake up and realize I need to do something about it. I then focus and improve myself to the point that life is much more enjoyable, so enjoyable in fact that I experience little pain produced by desire, anger and fear. But with such spiritual attainment, I forget to improve myself, and regress again. I find it pathetic that I need such basic, built in reminders as spiritual pain in order to motivate myself towards spiritual advancement. Do you have a clue as to how to continually improve, even after the pain is left behind? I suspect that my cycles are moving upwards, because I become more sensitive to spiritual pain with each cycle, but is it possible to advance without periodic regression?
In practice, however, we are lazy. Hence, we mainly work on ourselves ONLY when we HAVE TO. As you noticed, doing nothing leads to some regression. Then, our Higher Self arranges some interesting challenge for us and we need to choose - either to ignore the challenge or face it, solve the problem and advance ourselves.
Regressing and suffering seem quite efficient alarm bells for re-evaluating and re-thinking our attitudes. For this reason I think that at our level of conscious evolution both of them are absolutely necessary.