Faith is a Gift and a Commandment

Mosiah 5:4 And it is the faith which we have had on the things which our king has spoken unto us that has brought us to this great knowledge, whereby we do rejoice with such exceedingly great joy.

The people had faith on the teachings of King Benjamin and because of that faith, they were blessed with great knowledge which gave them exceedingly great joy.

We know that faith is the first principle of the Gospel, according to the 4th Article of Faith.  Ponder on this statement from the Church website:  In order for faith to lead to salvation, it must be centered in the Lord Jesus Christ (see Acts 4:10-12; Mosiah 3:17; Moroni 7:24-26; Articles of Faith 1:4). We can exercise faith in Christ when we have an assurance that He exists, a correct idea of His character, and a knowledge that we are striving to live according to His will. 

Many books have been written about faith, but I'm not sure I really comprehend it.  I believe faith is a gift that God gives to us when we seek Him and are obedient.  It starts as a small seedling, as Alma described in Alma 32, but it is our responsibility to nurture it and feed it and exercise it.  We do those things as we study His Gospel and ponder on His teachings and continue to be obedient.  We must be "anxiously engaged" in many good works.

Exercising faith doesn't sound like a spectator sport.  We can't be lazy and complacent to exercise our faith.  We must be proactive in doing good things.  But it doesn't take much faith to travel along a smooth road.  It's when the road gets bumpy and hilly that things get hard.

Boyd K. Packer gave a talk called Candle of the Lord.  He's talking here about how to gain a testimony.  "Somewhere in your quest for spiritual knowledge, there is that “leap of faith,” as the philosophers call it. It is the moment when you have gone to the edge of the light and stepped into the darkness to discover that the way is lighted ahead for just a footstep or two. “The spirit of man,” as the scripture says, indeed “is the candle of the Lord.” (Prov. 20:27.)"

I believe this applies to exercising our faith.  We must sometimes "step into the darkness"  in our obedience in order for our faith to grow.  Then the Lord will bless us with more faith, and the cycle will continue.