from an article by gloria copeland on healing

Faith in Two Places
"I'd have no problem at all believing God's Word would heal me if He'd speak to me out loud like He did in Genesis," you might say, "but He hasn't!"

No, and He probably won't either. God no longer has to thunder His Word down at us from heaven. These days He lives in the hearts of believers, so He speaks to us from the inside instead of the outside. What's more, when it comes to covenant issues like healing, we don't even have to wait on Him to speak.

He has already spoken!

He has already said, "...By [Jesus'] stripes ye were healed" (1 Peter 2:24). He has already said, "...I am the Lord that healeth thee" (Exodus 15:26). He has already said, "The prayer of faith shall save the sick, and the Lord shall raise him up..." (James 5:15).

God has already done His part. So we must do ours. We must take the Word He has spoken, put it inside us and let it change us from the inside out.

You see, everything--including healing--starts inside you. Your future is literally stored up in your heart. As Jesus said, "A good man out of the good treasure of the heart bringeth forth good things: and an evil man out of the evil treasure bringeth forth evil things" (Matthew 12:35).

That means if you want external conditions to be better tomorrow, you'd better start changing your internal condition today. You'd better start taking the Word of God and depositing it in your heart just like you deposit money in the bank. Then you can make withdrawals on it whenever you need it. When sickness attacks your body, you can tap into the healing Word you've put inside you and run that sickness off!