Usually, what happens for me is, I spend from 10-6 working on my Master's thesis or occasionally distracted, I spend from 5:45-7:30 playing Ultimate (a running sport with a frisbee) with some friends two days out of the week, I hop down to the stores before they close, at 9pm I get home and cook myself dinner. The days where I don't exercise are sometimes spent working later on the thesis, since I can get distracted on the Internet while at work and nobody bugs me.
That last point is I think the single most significant thing that you have to establish. When someone wants it, you will find it much easier to continue. Most of my projects are unwanted, and are therefore on the back-burner.
I don't mean to blend religion with Hacker News too much, but it is very important to me that we realise the power of ritual, and what we take for granted. So it is just taken for granted that my phone will go off with an alarm at 11:30pm, and then I will change into comfortable evening clothes, brush my teeth, turn off the computer, sit down on a meditation cushion with a pen and paper, and write. These are usually religious writings, and I don't want to get into that too much here, but the ritual, as well as the great importance to me, helps me to practise this skill. Setting an alarm on your phone is a good idea because it can interrupt the distractions.
As for those side projects, what really helps for me is that I walk to my apartment and back. Whenever I talk about the fact that my primary transportation mode is walking Hacker News seems to have pretty tepid responses -- "why not bicycle or drive home and then sit for half an hour instead?" -- but the distractions when walking are very different. Sometimes, I practise my singing on the way home, with music from my mobile. That's generally an indication that my brain wants some rest and I should watch television or read a book. Other times, I am thinking about a physics idea, or superpowers, or one of my projects -- then after dinner, my goal is to sit down at my laptop and write something on those projects.
I think we need to learn two skills of resolve. One of them is flow, focusing one-pointedly and whole-heartedly on something and loving it to death. (Love is always transformative and gives our lives worth and meaning.) Another one is reflection, breaking out of the things which we take for granted and casting them into the void. It is by voiding the distractions that you see the messiness of the room; it is your love of the room that makes you clean up the mess. That is not a complete guide to an authentic life, but it is the most important for what you have asked.