Howbeit this kind goeth not out by prayer and fasting-Matt 17:21
This teaching seems to indicate there are some problems, some challenges, some demons so great that an extra measure of faith and power is needed. In Jesus the Christ, James E. Talmage teaches this principle:
Have you some besetting weakness, some sinful indulgence that you have
vainly tried to overcome? Like the malignant demon that Christ rebuked in
the boy, your sin may be of a kind that goeth out only through prayer and
I have written about the power I feel fasting has had in changing my life. The key component of recovery and true gospel change is faith in the atonement and healing power of Jesus Christ. Maybe the secret of prayer and fasting is the building of faith that comes through it's power.
I do know that with an addiction as damaging and controlling as mine...and perhaps with whatever struggle you are dealing with...these words may provide the added measure of strength needed. "This kind goeth not out but by prayer and fasting".