To exercise faith is to act- to DO something- such as study the scriptures, pray often and earnestly, be baptized, attend church, serve others, keep commandments and commitments, repent, etc.
In "Preach My Gospel" it reads:
"Faith in Christ leads to actions. It leads to sincere and lasting repentance. Having faith causes us to try as hard as we can to learn about and become more like our Savior."I am always impressed with the faith that the newly arriving missionaries bring to missionary work. They have an unwavering faith that the field is white and ready to harvest. They energize us and remind us to continue in that unwavering faith.
President Thomas S. Monson said: