Stealing time to write

Here's where I've been able to eke out writing time lately:

at 6am, for about an hour, on mornings when I can convince myself to wake up an hour early. On the train to work, for about twenty minutes, using my thumbs on my phoneThe same on the way backSometimes for an hour or so before bed, if I can get everything done 

It's gotten to the point where I don't mind having to trek across town to do some annoying errand if it means I actually get fourty minutes on a train. 

I know the area I'm missing: large chunks of uninterrupted time in an evening or a weekend where I can sit and write and not worry about anything else. But I don't know how realistic that is with a full time job, a relationship, and freelance work on top of it. I always feel like I'm stealing from my life in order to take time to write, but I know if I don't, my life is going to get worse (emotionally, mostly). 

Other writers, how do you do this?