Romans 15:13

Now may the God of hope fill you with all joy and peace in believing, that you may abound in hope by the power of the Holy Spirit.

Faith is most important in order to gain hope; for if one does not believe in God and in His Son Jesus Christ there is no hope for him at all.  Then, in believing, joy and peace are given as well.  But there are two more elements that bring us hope: the Holy Spirit and our prayers.  The power of the Holy Spirit working in our prayers keeps us believing, makes our joy and peace perfect and full, and likewise, gives us an abounding hope.

So the way I see it, whenever we feel down and without hope, we need to call on the God of hope. 

Ask Him, in the power of His Holy Spirit to help you believe and to fill you with His joy and peace—with all the joy and peace He has for you.  Then, according to this verse, you will abound in hope.