The Romans called it tempus fugit, literally translated as 'time flees' or 'time escapes' or more colloquially, 'time flies.'
Many people ask me how I stay focused and productive when writing from home when there are seemingly so many distractions around beckoning for your attention.
It may have been my many years working as a project manager or military officer. Still, I always found that the key to staying focused when writing and working from home or doing anything worthwhile is having an effective time management plan and jealously guarding your planned schedule.
Time management is not time tracking. When people start a new hobby, activity, 
study, or creative endeavor, they can often get over zealous with what they will achieve. They try to religiously keep track of everything they do every minute of every day. That is not time management- that is slavery.
Life happens, and there are times when you need to adjust your plan for a particular day. The most important thing is, continually without fail come back, refocus, and tweak things as you need but never stop working towards that ultimate goal. Become your own life project manager and treat your writing as seriously as you would any job, degree, performance.
As one of my favorite stoic philosophers, Seneca said, "It is not that we have a short space of time, but that we waste much of it. Life is long enough, and it has been given in sufficiently generous measure to allow the accomplishment of the very greatest things if the whole of it is well invested."
Usually, your biggest enemy is not your boss, work, children, manager, or teacher but rather your lack of proper time management. We often aren't willing to put in that same extra effort for ourselves as we would say at work, school, other for other people, and the list goes on. This mindset of not taking your work as seriously as you should limits focus and progress because we allow ourselves to put tasks off until later. Again, you need to become your own project manager and stick to the plan.
This is very insightful. I might try this philosophy.