Tip: Have everything in place before you start.
There's a French cooking term mise en place which means to gather all your ingredients & do your prep work before you start.
This is highly useful when you're working from home. Make sure that the printer has paper, that you have all the items from work that you might need with you, and get to work.

It's too easy to let yourself get sidetracked by thinking you need something. Plan your tasks, and take it one task at a time. Then plan ahead for what you need.

If I know that I will be coding some JavaScript, I have my two favorite reference books nearby, I get a glass of water, and I sit down at the computer until it is written, debugged, and integrated.

If I am cold calling to drum up business, I go to the bathroom, get a glass of water, get my list with lots of paper, put a huge smile on my face, and start making phone calls.

Walkaway:
Decide what your task is
Get everything you need
Work at it until you're done
(yes, that does mean don't answer the phone barring emergencies and don't peek at your email)