For me my faith is linked to my religion. I have faith in God because my religion tells me to. God has shown me the way when I have need it the most, so I think that has helped my faith along as well. There are times that I struggle with my faith because I am struggling in life and not getting what I want out of it, but at the end of the day I know that if I pray and have faith in God that he will pull me through it.
I also define faith as what you have in other people. I have faith in certain friends and family members that they will be there for me, do the right thing and be around when I need them. When someone disappoints me or upsets me, I lose faith in them, and once that faith is lost, it is hard to be revived.