Luke 17:5-6  (NKJV)

5 And the apostles said to the Lord, “Increase our faith.”
6 So the Lord said, “If you have faith as a mustard seed, you can say to this mulberry tree, “Be pulled up by the roots and be planted in the sea,” and it would obey you. 
Are you concerned that you do not have enough faith to get the job done, and you are asking God
for more faith? Well, the reality is, you have enough faith already to move mountains.  When God
gave you His faith to receive the greatest miracle that will ever happen in your life, you became
a world overcomer.
Romans 12:3  (NKJV)
……God has dealt to each one a measure of faith.
Romans 10:17  (NKJV)
17 So then faith comes by hearing, and hearing by the word of God.
When you heard the gospel (the good news), God’s gift of faith came into your heart which gave you the capacity to believe the truth; thus receiving salvation.
That faith was enough to deliver you from the powers of darkness and translate you into the Kingdom of God’s dear Son (Col. 1:13). That is the kind of faith you have in your heart, world overcoming faith. So, if you are struggling where faith is concerned, it is not for a lack of faith; it is a lack of knowledge.
Hos 4:6  (NKJV)
6 My people are destroyed for a lack of knowledge.
Let me explain what I mean when I say that you have a knowledge problem.
Hebrews 11:1  (NKJV)
Now faith is the substance of things hoped for, the evidence of things not seen.
You see, faith can only give substance to the things you would hope for, and hope comes from the Word of God.  When you hear the gospel, the good news, it paints an image of what you have, what you can do, and who you are in Christ Jesus in your heart; that is hope. In other words, you can-not exercise faith for something you do not know that you have.

You need the knowledge that Jesus redeemed you from the curse of the law (Gal.3:13), that Jesus bore your sickness and carried your diseases Matt.8:17) 

by His stripes you were healed (Isa.53:4). That He sent His Word and healed you and delivered you from all  your destructions (Ps.107:20). Faith comes by hearing the Word of God. When you increase in Knowledge, you will be able to exercise the faith that you already have in your heart for more of God’s grace, more of the promises of God which will enable you to partake of more God’s divine nature (2 Pet.1:4).
2 Peter 1:2  (NKJV)
2 Grace and peace be multiplies to you in the knowledge of God and of Jesus our Lord,
Without the knowledge of God and of Jesus our lord, we will not have the faith to access God’s grace or peace (Rom. 5:2).
Begin to immerse yourself in the Word of God and begin to explore the things that God has freely given to you.