Those of you with day jobs, how do you find the time/energy/motivation to work on your side hustle in your free time?

Work on a subject you love, and hustling will become far more simple to do than playing video games or watching Netlix. Also, one thing that's working for me (but I think it's possible because I'm single, and working in Paris so my home is not very far from my job) is to go to my workplace early or stay like 1h later than usual, so that I can work on my side-projects in a calm and distraction-free environment.

go to my workplace early or stay like 1h later than usual

In the US this would make any IP you develop for your sidehustle automatically belong to your employer AND you'd be expected to work on work stuff while you're there.

Oh crap, didn't know that. In France I'm even working on my company's MacBook and the work still stays mine according to law :p

It's okay, most employers in the US put a clause in your contract that says your IP belongs to them regardless of whether you develoepd it using company equipment or not. The nice thing about CA is that this clause is illegal and unenforceable (they still put it in there just in case you're easily fooled)

lol free time

Sorry, I should have said "the time you should spend sleeping"

After work, I head over to Starbucks or the library for an hour or two. If you have a family, take 1-2 nights off during the week day for balance. Treat it like a second job otherwise your projects will not take off.

I think getting out of the house is a good idea! I usually tell myself right as I'm leaving the office that I'll work on something when I get home, but I no longer feel like it once I sink into my chair at home.

I was always most motivated when my side business was really growing and getting attention -- people telling me they loved it, getting new customers, etc. But the majority of the time that motivation didn't land in my lap; I just had to sit down and do it. I'd usually do a weeknight or two of staying up till 3am, just working for 8 hours straight after the day job so I could push my stuff forward a bit, and that helped.

Ultimately it doesn't matter if it's a side hustle or art or whatever you're doing, you just have to find a way to do it and not worry about time or motivation. Here's a good video on the subject that explains it really well.

That video was really good; very insightful.

On a more serious note, I recommend listening to this podcast. Seth Godin makes a bunch of great points about just this sort of thing…

I keep a pretty solid routine during the week: wake up at 6 and sit down and code and work on my little project until it's time to go to the office, around 9. Those are solid two hours of uninterrupted work every day. After work, I still put in one or two hours and that still leaves me time to Netflix or cook or read a book before going to bed at 10. But that's only possible because I am super excited about it, which makes these the coolest moments of the day.

And on weekends again, lots of time to put into it in between hanging out with friends.

It is not nearly as much as I want to put into it, but I have to work with what I can :)