[jwatte]

So what are you doing when not working? Maintaining a house? Watching TV? Stuck in a commute? Taking care of elder parents? Volunteering at the red cross? Raising a family?

Give up something you value less than development. Move closer to remove commute. Let someone else volunteer. Give the family involuntary free space.

How about: Find or make an alone space. Set aside 12pm to 10pm every Sunday for your project. You disappear from the world, and only do the project. No maintenance/family/commute/charity/TV is allowed to interrupt.

This gives you 10 hours per week, or 25% of full time. If you spend half of your working time in unproductive meetings, it's more like 50%.

It can be done. Is it what you want to do?