One of the promises that God has given his followers is that He is faithful and will answer out prayers. The power of prayer is one of the cornerstones of faith However, there are times that believers seemingly do not receive what they ask for. The pat response is that God sometimes says "No," or that what you are asking must not be in Gods will, and at that point you stop praying. But is this in line with what God has promised, or is it just spiritual laziness?
In Matthew 15:28 Jesus rewards a woman and grants her request because she was faithful and continued to ask, even when she did not at first get what she requested. God does not always give you what you ask for when you first ask. He wants you to grow in faith. That means believing your prayers will be answered even when your prayers so far have been unanswered.
Developing your faith is similar to building strength in any other area of your life. You have to work at it on a regular basis. If you are trying to build arm strength, but stop lifting because the weight is heavy, your muscles will not get stronger. The same is true with having faith in your prayers.
When you cease praying for something because your prayers were unanswered after the first couple of times you ask you start to develop a habit of expecting your prayers to go unanswered. This isn't faith; it is a way to excuse your own lack of faith.
The Bible is full of promises that if we are faithful in our prayers, and if we have faith that our prayers will be answered, we are assured that the Lord will give "more than we can ask or imagine" (Eph. 3:20).
Pray diligently. Don't quit at the first sign of resistence. God rewards your persistence when you pray in faith.