Well, that's on you, but the good news is that you can change that as soon as you want. Why not start today?
For me that is writing poetry and making music for myself, which I randomly stumbled upon after having had so many other hobbies in the past besides programming
- sports is an obvious one. Bonus points for team sports where you'll get a different community / social circle for free
- as others suggested music is great way of playfully easing into different activities. A fun start would be Melodics ( https://melodics.com ). If you'd like to keep it close to programming take a look at Max/MSP. Play around with a software synth, or get a hardware one like Korg's entry level offerings. If you'd like to move up to advanced levels, take a look at Ableton Live + Push, which is a very play- AND powerful way of learning a DAW.
I’m speaking to myself, BTW. I have spent a good portion of my life of explaining it to others and questioning it myself. I started programming in the 80’s though, and I had to fight through a wall of people with the mindset that computers were inherently “evil” and treated with high suspicion because they were not commonly understood. Yes, I grew up in a backwater.
Do all people who paint water colours also have some other totally different unrelated hobby they are just as passionate about, like motorcycle restoration? I'd wager not.
For me, running became a sort of "hobby" as such - I guess you could call that "sport". What were the other things you were thinking about at school when you "played it safe"? Never too late to learn/relearn things.
Digital signal processing and music for example.
I suppose cooking might have actually been the best avenue. I find that the more i cook the more i draw parallels. It's quite associative and borderline object-oriented. I watch cooking shows where a dish is mentioned and the chef immediately starts building a menu in his head. It reminds me of when someone asks a programmer to design a blog/website/etc.
No matter how much someone directs you on how to program something, you always have that little bit of wiggle room to add your own creativity to it.
Programming is like art. The coding is the medium. The thoughts and solutions, when it all works together, just feels right.
My job when it goes into stuff other than programming, I find myself coding at night to feel that structure, control, creativity and freedom all rolled into one.
Most other fields don't offer that.
If not programming, that 20% of your brain would have been thinking about whatever else it is you did for a job.
By default, this "computer brain" of mine is carried with me when I leave work. I have to make a concentrated effort to context switch back into "real life" mode (similarly how I have to context switch into "computer" mode). I think that's why so many of the good programmers are a little weird and introverted, because they don't bother to context switch back.
Art is art!
I wonder what that fifth of my brain would have been thinking about for the past 10 years, if not programming. Maybe it would have been dancing, or painting, or soccer. Instead of context switching into thinking like a computer, it'd be how to move my body around or how to meld colors together. I feel like that would lead to a much more fulfilling life.
I used to program for fun in middle school. It was probably halfway through high school when I stopped programming for fun. It was always that little nagging voice in the back of my head: Play it safe. Programming is an in-demand field! You're good at it! Look at all of that awesome shit you made.
At this point, the only "hobby" I have is programming. I don't even know what else I like anymore.