Matt17:21-However, this kind does not go out EXCEPT by prayer fasting.
The disciples of Jesus prayed for someone without result, later they met Jesus and asked Him why they couldn't deal with the demon behind the problem, Jesus simply told them that 'THIS KIND(of demon, sickness, problem) does not go out EXCEPT by prayer and fasting.
For example, if your power rating is 3voltage and you're dealing with a demon operating at 5voltage, you'll need extra power. Does it mean demons are more powerful than the least believer? NO
What actually happen is that when we fast, the power deposit in our spirit-man is released and the flesh is subdued so that we can operate at a higher level of anointing, that's why you sense a stronger anointing after a very long fast.
If you have prayed, sown seeds and tried your best on a pressing issue without solution, just know that it is a kind that won't go out until you fast&
Pray.
Find time to pray and fast about those pressing issues.