Matthew 7:7-11 (NIV):  “Ask and it will be given to you; seek and you will find; knock and the door will be opened to you.  For everyone who asks receives; he who seeks finds; and to him who knocks, the door will be opened.  “Which of you, if his son asks for bread, will give him a stone?  Or if he asks for a fish, will give him a snake?  If you, then, though you are evil, know how to give good gifts to your children, how much more will your Father in heaven give good gifts to those who ask him!

The context of Jesus’ promise is important.  The promise that God will “give good gifts to those who ask Him” is living in the kingdom of God (the context of the whole Sermon on the Mount).  It is not carte blanche to ask for material blessings or a “wish list”.  Jesus’ own example is someone asking for food.  Those who ask for the necessities of life, or for what they need to do the work of the kingdom will receive.  The context for these kinds of requests if found in the prayer of the kingdom:
Our Father in heaven, hallowed be Your Name (Oh, how few passionately pray that God’s name would be hallowed, made holy.  If they would really ask for this, God would hallow His name through them by doing glorious things!)
Your kingdom come, Your will be done on earth as it is in heaven. (This is not a petition for Jesus’ return, but for the kingdom of God, which exists in the heart and life of every Christian, to be made manifest – for “the kingdom of the world (to become) the kingdom of our Lord and of His Christ.” (Revelation 11:15)  It is a petition that God’s will would be done on earth as fully, immediately, and willingly as it is done in heaven.  If God’s people would actually pray for this (not just mouth the words), He will make it happen.)
Give us today our daily bread.  (This is a petition that many are unwilling to actually pray as it stands – bread for today; not for tomorrow or next week, but simply what is necessary each day.  Jesus had not pantry or refrigerator.  He trusted God to give Him each day just what He needed, and the Father answered Him.  Every day He received exactly what He needed for that day, just as the Israelites received the manna in the wilderness.  Oh, what blessings God could give to His people if they were willing to ask each day for their daily bread!)
Forgive us our debts as we also have forgiven our debtors.  (This petition comes with a condition – that God will forgive sins in the same way that the asker has forgiven others.  And that is exactly the way He does forgive (see Matthew 6:14-15).  If a person is fully forgiving of all wrongs done to them, then God fully forgives their sins.  If they do not forgive others, if there are any grudges or bitterness against others in their hearts, then God fully answers their prayer by NOT forgiving them.)
And lead us not into temptation, but deliver us from the evil one.  (God will definitely do this for anyone who actually asks.  He is the only one who can deliver us from the enemy’s hand, and he promises to never let one who really prays this prayer to be tested beyond what they can endure – He will always provide a way out, so that they can be victorious every time.  (See 1 Corinthians 10:13.))
God will always give these good things to everyone who asks for them from the heart.

Father, this is an amazing promise.  Forgive us for too often mouthing the words of this prayer, instead of really asking from the heart.  Forgive us for asking for “stuff” instead of asking You to hallow Your name through us.  Forgive us for asking to be kept safe and healthy instead of asking for Your kingdom to be made a reality on earth, no matter what it takes.  Forgive us for asking for security for tomorrow instead of asking for just what we need each day, making ourselves totally dependent on You.  Forgive us for asking for forgiveness when we have not fully forgiven others.  And forgive us for too often assuming that You will give us the victory over the enemy without actually asking for it.  Help us, Lord, to turn only to You in all of our asking, seeking, and knocking.  Amen.