Training myself, raising a watchdog in my head that periodically asks "is this useful?". Whenever I find myself refreshing some social medium like hn, I think "is this useful?" No, I respond, and I close the tab. I'll just force myself to read a bit about something, or at least alt tab to the editor, or what have you. Sometimes progress is agonizingly slow. But it's progress, and not a full day wasted on the net.
It helps to have a to-do list at hand with small, clearly defined, reachable goals that I can then immediately start work on, such as "read 5 pages of book X" or "finish writing the prettyPrintFizzBuzz function".
It helps to have a to-do list at hand with small, clearly defined, reachable goals that I can then immediately start work on, such as "read 5 pages of book X" or "finish writing the prettyPrintFizzBuzz function".