Right now, this very moment, I'm just writing and letting my thoughts flow. This usually doesn't happen. I always think of various other stuff I should be working on while performing a particular task.
Other days, I would open my laptop, check e-mails, blog subscriptions, my blog stats, Facebook, Twitter, messages, etc. I would then think about writing and while writing I'd think about other activities I should perform.
I have tried decluttering and letting go of lots of unnecessary stuff in the past. I'd do it and after some months, it would come back again in another form. If I stopped using Facebook, I'd forget about it and use it again after some time. Or I end up in situation where I have to use Facebook and I start using it again.
This pattern made me realize that we need to keep decluttering stuff time and again. It's never over once and for all. It comes back one way or the other, and we need to declutter again and again.
Just working and focusing on one thing seems very easy, but when we have to go through it, it's pretty difficult. Unless we are enlightened, we won't be able to focus on one particular thing all the time. We will go back and forth between stuff.
Regarding this, are you only focusing on this post? or are you thinking about something else while reading this? If not, focus on this line, this sentence and this word.
Another activity I like to perform is to look at different elements in the room. Look at the wall and only focus on it. Don't think about anything else.
Now look into your life. Are you always focused on the work you are trying to do or are your thoughts scattered over the place. Make sure you are on trance like state focusing on your work. If not, start decluttering. Look for spaces where you can improve upon.