It's sad that you are in position where you are forced to work 8+ hours cause it will only hurt you in the long run.
I don't think it will necessarily hurt most people to work 8 hours/day. After all, 8 hours is just a regular work day for those with "real" jobs (and that's without commutes and such).
Would it really adversely affect someone in the long run? It was my impression most indies spend even more time than that.
actually, 8 hours *isn't* normal for people who work 8 hours a day. they have lunch breaks. they often don't work every single minute of that time, often having breaks for meetings or goofing off on the job. there was a study that measured actual work in the typical 8 hour workday / 40 hour workweek, and they found something like only two and a half hours of actual work got done, the rest of the day, even for *salaried employees* was wasted on distractions, breaks, periods where they did nothing and stretched or went to the bathroom or drank coffee, travel time, walking between rooms, time spent socializing with other co-workers, time spent staring off blankly into space, etc.
so it really depends on how an indie measures "working 8 hours". i feel it's impossible, long-term, to work 8 hours a day without breaks or distractions of some kind. if it's impossible even for those being paid for it, so how would it be possible at home when nobody is watching you?
also, valhalla, working 4 months at 8 hours a day certainly is doable, but is it doable long term? could you do 30 years of it? you might "burn out" after a number of years. i've found that about 3-5 hours works best for me, any more than that and the quality of my work suffers. i don't force myself to only work 5 hours a day if i'm feeling particularly motivated, but i don't feel bad if i only do 3 hours a day either. three *good* hours a day is still more work than most people who have a salaried job do (since those actually average two and a half hours of real work per day)
for time management i suggest the pomodoro technique: http://en.wikipedia.org/wiki/Pomodoro_Technique
-- it breaks time up into short 25-minute chunks that must be uninterrupted or they count as void. it trains you to avoid interruptions and to focus, as well as to organize your time
another issue is that in the long-term, in creative fields like game design, nobody cares how hard you work, they care only about the quality of what you produce. take writers: if you're a writer and work hard you can release a new novel every year. and some writers do that. but when they're dead, most of their average or bad novels are forgotten, they're remembered only for their one or two best novels. and even while they're alive, 90% of their income will come from their one or two most popular novels, not from the vast body of their work. people read philip k. dick because of a scanner darkly and do androids dream of electric sheep, and a couple of other stories and novels, not for the man who japed, dr. futurity, humpty dumpty in oakland, or for most of his 44 novels. except for hardcore pkd fans, nobody has read all 44 of his novels. i feel it's more important long-term to ensure that what you do is top quality (without being so much of a perfectionist that it's never released) than that you create a lot of stuff or that you get it done fast
also keep in mind that indies tend to work on their game every day, not just five days a week the way that people who work at a salaried job do. if you work 5 hours a day, 7 days a week, that's almost as many hours as 8 hours a day, 5 days a week. i feel that the habit of working on your game every day of the week (even weekends) is pretty important to keep the momentum of a game going, and if you work every single day rather than only some days, time adds up differently (40/7 is 5.7, so if you want to work 40 hours a week you only need to work 5 hours and 45 minutes every day)
regarding distractions, i find that if you take more breaks (intentionally) you have fewer unintentional distractions. if you are conscious of what is work time and what is break time, and know that break time is coming up very soon (less than 25 minutes away at all times), you don't get as distracted. but also important is that if you are conscious of break time, and conscious of every distraction (through the pomodoro technique), you realize that a lot of distractions aren't worth your time. after i started using that technique, i found that i had just as much time not working as before, but the time i didn't spend working was spent better: my break times were spent reading good books and playing great games rather than reading internet articles or watching youtube, for example