And Jesus, replying, said to them, Have faith in God [constantly]. Truly I tell you, whoever says to this mountain, Be lifted up and thrown into the sea! and does not doubt at all in his heart but believes that what he says will take place, it will be done for him.
(Mark 11:22-23, Amplified Bible)

You can limit the very power of God in your life by your lack of expectancy.  You will never receive beyond your expectancy.  Jesus said to him, “If you can believe, all things are possible to him who believes” (Mark 9:23).  I remember years ago I was praying for a mother of a boy who fell and broke his front teeth. They needed to find a dentist that would take payments each month because they did not have the money.  When I started to pray the Lord Jesus spoke out in a audible voice and said, “Stop! You are limiting me by praying for a dentist to show favor.”  He added,  “Don’t limit Me; Instead, pray for a creative miracle.”  The next day two new teeth appeared in his mouth!

Because of your unbelief; for assuredly, I say to you, if you have faith as a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you.
(Matthew 17:20)