If Christians are saved by faith alone, then why does Jesus want Christians to do certain things?

I have wondered that if it is faith alone that gets a Christian into Heaven, then why was it important to Jesus that his followers do certain things such as obeying His commandments and caring for their fellow man? Case in point, consider these two Biblical passages: _"Whoever has my commandments and keeps them, he it is who loves me. And he who loves me will be loved by my Father, and I will love him and manifest myself to him.”_ -- John 14:21 _“Then the King will say to those on his right, ‘Come, you who are blessed by my Father; take your inheritance, the kingdom prepared for you since the creation of the world. For I was hungry and you gave me something to eat, I was thirsty and you gave me something to drink, I was a stranger and you invited me in, I needed clothes and you clothed me, I was sick and you looked after me, I was in prison and you came to visit me.’_ _“Then the righteous will answer him, ‘Lord, when did we see you hungry and feed you, or thirsty and give you something to drink? When did we see you a stranger and invite you in, or needing clothes and clothe you? When did we see you sick or in prison and go to visit you?’_ _“The King will reply, ‘Truly I tell you, whatever you did for one of the least of these brothers and sisters of mine, you did for me."_ -- Matthew 25:34-40