We love previously covered Simple Desktops for attractive, distraction-free wallpaper, but if you want to go both minimal and motivational, or just find some other great options for your desktop, you'll want to check out Minimal Wall.
Minimal Wall often focuses on a single colour desktop with a brief word or two to offer up some motivation. Sometimes it's just a few simple colours, like you can see in the picture above (and download here). Minimal Wall is really more of a process than a wallpaper site, however, as they offer up steps to simplify your desktop and other helpful information. This way your new wallpaper isn't just about decoration but about actually making your desktop a cleaner and more productive space.