Do it.
3 hours per day, 5 days a week for an entire year is 720 hours. It's a marathon, not a sprint. And it's not like you need to always do it. Try it out, see if it is for you, worst case you cross the idea off your list.
Maybe a polarizing opinion, but if you put yourself in a box that “doesn’t have enough time” just because you have a commute, are a parent, [insert other excuse here], then it’s the equivalent of sitting at the start line and watching everyone, even the walkers, tread ahead. It's okay if that's what you want, but it is a choice.
I would guess in an average week, I have about 5 quality hours where I do not have an obligation to someone or something else and am able to spend it as I see fit.
As a New Years Resolution, I've been getting up at 5:30 each morning to get 1.5 hours to do my own thing in the mornings, and so far it's been going well. I would still like more time, but constantly getting small amounts done is a great motivator.
I also start a new job in a few weeks that is 4 days a week so I can spend a full day each week on my project. I'll take a small financial hit, but I'm hoping that will be enough to get something worth shipping out the door. If it all goes up in flames, I can always go back to full time without having risked too much.
Just a suggestion. It has worked for me before, but I am with you in general. Most days in the 1.5 hr "me" time that I have, Netflix/Hulu on the couch/chair with an IPA sounds pretty great at that point :)
630a - 8a: get myself ready, get kids ready
8a - 630p: commute and work (yes, the author does say she eliminated her commute, but this isn't feasible for everyone)
630p - 8p: dinner, get kids to bed
8p - ~9p: dishes, general cleanup, pay bills, etc...things most adults have to do to live
9p - 1030p: 1.5 hours of "me" time if we're going for 8 hours of sleep...no, more like...
9p - 12a: really the only window I have to live. often spent doing more work and really, usually too brain dead to start a side project. again, adulting and parenting are hard and energy intensive. Netflix sounds really good at this point.
1030p - 630a: 8 hours of sleep (haha - i'm really trying to live somewhat of a life so 1130/12 is a more regular bedtime)
I've been considering the 10p bedtime/5a wake up so I can do side projects in the morning, but this still only adds 1.5 hours of time for a total of 3 hours a day.