Personnaly, when I feel like wandering off, i let it go. I stop working even if it has to be for 1 or 2 hours. Once I feel I had enough, I take a huuuge cup of coffee (or energy drink, your choice), then I get back to work. When I come back to it, I realize that I have a lot to do in a short time (since I did nothing for the past 2 hours), and the caffein is kicking in. That's when I'm the most productive, and how I manage to get things done.

A more succinct way of asking what you're asking is "How do I keep focus?"

Answer, it's a matter of discipline to attention. How to do those? Lots of practice and lifestyle changes. Reduce distractions and opportunity for distractions.

One "hack" is the pomodoro technique. Do about 20 minutes of work, then take a five minute break. This avoids burning out trying to work for hours on end, finding that you've accomplished very little.

Yea, I know this one. My boss is also suggesting us to do this technique :) Very effective.

Stop what you are doing and relax; let your mind wander. When your mind is ready, get on with what you are doing.

For me that's the best hack. It can produce quality results. Don't force it. That way, you will love what you are doing.

there's browser extensions that you can block certain sites for a period of time(to go off from the pomodoro technique)