"Now to Him who is able to do exceedingly abundantly above all that we ask or imagine (think), according to the POWER that works in US, to Him be glory in the church by Christ Jesus throughout all ages, world without end." - (Ephesians 3:20-21).
And how does a born again Christian ACTIVATE or TAP INTO this POWER available to them in God when they are suffering from mental and physical torment?
There are different ways to approach it, but one of the time-tested means of receiving deliverance and healing from God is by implementing the principles given in a booklet produced by the ministry of NEIL T. ANDERSON. The title of this booklet is: THE STEPS TO FREEDOM IN CHRIST.
Most Christian bookstores will be happy to order it for you. Many Christian counselors have access to it.