The benefit of having faith in God is well...salvation for one with a promise of everlasting life and inheritance of the greatest kingdom to ever exist. In a more worldy sense, faith in God is to have absolute peace. If you put your full faith in God, there is very little you ever have to worry about. You still have to manage your life, like balance your check book, go shopping, make sure you are staying healthy etc, but you can live without fear. Knowing that all you have to do is trust God and he'll hold you in the palm of His hand is to live a life with no fear. You don't have to worry about being sick, either you'll get better through God's will, or you'll die and be face to face with your Creator. You don't have to worry about starving or freezing to death, because if you seek Him first, He'll give you everything you need, even if it's release from life to be with Him. Imagine living without panic attacks, without worry, simply enjoying life the way God wants us to.
How do you gain it? It's not something you find in the store, it's not something you simply acquire, it's something you learn gradually over time. It's a matter of every time you worry, closing your eyes, saying a prayer, smiling, and simply giving it up to God. Push it from your mind and watch as He opens the doors. Even though He is opening the doors, you still have to go through them. Just because you have faith that God will help you pay your bills doesn't mean you can quit your job, sit at home, and stop sending checks to pay them. If you need something, God gives you a way to obtain it. Remember that. He wont' hand feed you with a silver spoon, but He'll make possible what He knows you need. Hold that in your heart, and like I said, when you start to worry, go to God. Just like when you were a child, what did you worry about ever? Nothing! You knew your parents were going to put a roof over your head, get you the clothes you needed, put food on your table, discipline you when you needed it, kiss your boo boo, teach you to do things you wanted to learn. So whenever you needed something, who did you always go to? Your parents! God is your Father, moreso even than your father on Earth. Think how much more He loves you than your own parents ever could even fathom. Go to Him like you would have your parents when you were 4. When you are hungry go to Him and He'll provide you food, when you are scared of the boogey man (or anxious about an illness or somthing) have God hug you and tell you it's okay and kiss your boo boo better. That's how you gain it, simply believing He'll help you, and then letting Him.