I think there's a lot of good advice here about how to build habits and routines in ways that will be sustainable and not too stressful, but when I hear you talking about a life of checklists I don't actually hear a problem that can be solved just with habits and routines. My advice is a little more personal, so feel free to ignore it if it seems off base, but: I wonder if you might consider beginning a ridiculous project or three.
Looking at my own beeminder gallery, I have two goals that are about routines -- a weekly medication, and flossing -- and the other (yikes) thirty-one are for things that aren't routine. Some of these are still dull life administration stuff, but most are things that keep me in touch with my bigger life priorities: staying in touch with friends and family, making progress toward ambitious career goals, learning new skills. And I have a good handful of weird little one-off projects.
Probably the best example of what I'm talking about here is a goal to read an eighteenth century French novel, in French, despite not really knowing French. When I cross "la nouvelle heloise" off my to-do list, it's not a checklist item, it's a baby step toward something that is a little bit silly but also a little bit awesome. (For graduate student definitions of "awesome.")
There's always stuff that has to be ongoing, but I like to Beemind by thinking of things I'd like to have done, and then setting the world's gentlest slope to encourage me to do them. If everything on your list is the kind of thing where you're just trying to maintain a status quo forever, if makes sense that the checklists feel like they're overwhelming your real life.
Hence my suggestion to experiment with a ridiculous project, something that it makes you smile to imagine yourself a year from now telling your friends you've done it. It probably won't make your day-to-day life any more spontaneous, but it might make the checklists more rewarding.