I have heard this so many times (the part about taking up time and mental energy) it’s a common thing.
As for freelance, I started on Upwork back when it was ok and built up contacts over time. I also built up a mailing list so when I needed work I’d just let everyone I know I’m available. That and some combination of referrals, Twitter and LinkedIn also did the trick.
For development work I imagine you’d have longer contracts. Mine were fixed engagement contracts.
About a month ago I accidentally deleted my account that had my mailing list so if I go back to freelancing I’ll be starting from scratch 😂 😭
TLDR; make good work. Make noise about it and share far and wide. Then let people know you are accepting work. Otherwise they won’t have a clue if you don’t make it known.