Work with goals, not with hours
In a typical office setting it is the norm to work for 8(+) hours no matter the task. Even if you've finished what you were tasked for the day you still have to fill your hourly quota. Since I've started working on my own I started working based on features instead. Today I want to have this specific feature done. At times it might take 8 hours, at times it might take 10, at times it might take 6.
This forces you to focus on the actual piece of work without splitting your attention over multiple tasks and without checking the clock.
If you work by hours you perform pointless tasks like checking your email or Skype too often just to feel like you're doing something but you're not actually working. You're just trying to find ways to procrastinate while looking productive.
It is harder to make that work in an office setting, but if you prove yourself as a hard worker the company might be more inclined in trying something similar. You need to show that you can still bring results and you can handle your workload deciding the hours yourself. It is not something suitable for everyone though so don't fret if it's not for you, there is nothing wrong with that.