100% Disk Usage

My computer is frequently plagued by disk usage at or approaching 100%, and despite all my searching, I cannot seem to find a solution to the problem. It bogs everything down, and frequently renders my computer nearly unusable. Anybody know what might be going on?

One first wild guess I have: I'm wondering if the computer is running a fair number of security [which includes constant real time scanning and real-time logging] and monitoring [which includes real time constant logging] programs in the background.
Downloading, installing, running MiniToolBox and Piriform's Speccy; saving the logs on your data drive, going through the logs will give you an accurate idea of what is automatically running in the background and what normally runs in the foreground as per choice by end-user. Do not post the logs! Only bits and pieces may be requested by others here.