Really helpful talk on the biochemistry of addiction focusing much on porn addiction but also showing how other addictions follow a similar neuropathway. See www.yourbrainonporn.com for more info.
As a Type Four I discovered that exercise is imperative if I want to avoid that gravitational pull to wallow in melancholy and other associated haunting swampy states. Wendy Suzuki nails the importance of exercise! I hope that this will inspire you to take on the task of exercising healthily and regularly.