Option A. Sit at your desk; connect to the Internet; access e-mail, social media, or read newspapers; then start thinking about what you were actually going to do at your workspace.
Option B. Sit at your desk, and avoid the Internet, social media, or other distractions; instead, write down what you need to do the following hour; do it; then leave your desk for a few minutes for a break; and repeat.
Clarify your tasks and do them before getting distracted with other stuff. The danger of mixing up work and distractions is to end up bringing both of them with you all the time, no matter where you go.