Hebrews 11 is an amazing summary of some of the old testament believers who lived by faith, it is worth reading when you need an infusion of faith. 

Now faith is confidence in what we hope for and assurance about what we do not see. (NIV Heb 11:1)

By faith we understand that the universe was formed at God’s command, so that what is seen was not made out of what was visible. (NIV Heb 11:3)

And without faith it is impossible to please God, because anyone who comes to him must believe that he exists and that he rewards those who earnestly seek him. (NIV Heb 11:6)