Full-time 9-5 developer here. I leave my work at work and spend my Sundays with my fiancee and my friends. I tend to either go for a run or play disc golf in the mornings, make a homemade lunch, then, weather permitting, spend the rest of the daylight hours outside at a park or hiking or shopping or anything that can get me out of the house. If the weather sucks, I'll go see a movie or something.

Last year, I spent a non-trivial number of hours working on costumes for Halloween and other events. I learned how to make soap from scratch. I wrote a novella (~45K words). I taught myself piano (very poorly). Basically, I just want to stay busy and learn a lot.

My personal philosophy is that work stays at work. I get paid for my 40-ish hours -- not my Saturdays and Sundays. Don't get me wrong: I don't mind working a bit late during the week, and I'm always the first one into the office. It's a good job, and I like it a lot, but I think part of why I haven't burnt out is that I have a clear separation between my work and personal life. If there's a weekend emergency, I'll respond. In my experience -- and I believe this is true for weekdays as well -- there's nothing that can't wait until tomorrow (or Monday, as the case may be on the weekends.)

Sunday is fun day. Saturday, too, for that matter.

"work stays at work" is perfect philosophy

Writing a novela! Awesome idea!

Back when I was in grad school I worked Sunday but took Saturdays off (not for any religious region)

Today I have a family and work at home and I usually work less on the weekends, but I often try to get a 2 or 3 hour session on each day, usually coding, almost never biz dev.

As for what I do for fun, I go for walks, play video games, watch a movie, go see family in the next town over, etc.

Rule #1 - No email or social media on Sundays!

Since most of my time is spent slouching over my laptop I use Sundays to escape to the outdoors. Having a dog is a great excuse to explore the wild and the fresh air clears my mind.

If it rains, I still try to avoid TV/Laptop in favour of getting creative in the kitchen or having a few beers and banter with friends.

I take my (three-month-old) son for a walk in his stroller every Sunday. It gives my wife time to herself to do whatever she wants, it gives me some bonding time with my son (well, once he's more aware of me being a thing that exists), and it gets me exercise and a reason to get outside.

IF I am behind on a project, I'll work on Sunday. Otherwise, I'm taking the day off.

Good weather > outside doing something (could be anything: photography, hiking, biking, etc)

Bad weather > sitting inside binge watching a TV show or playing video games

Pharmacist here, I spent Sunday's with Family, Ruby and some exercise :-)

Away from my computer as much as possible.