What is it that burns you out most? (fellow freelancer here)
[1]: https://remotetogether.slack.comDon't be afraid to say "no" to the client, especially if you have given them an honest estimate and they are pushing you to revise the estimate downward.
How do you land those roles reliably? I have no idea. Some combination of luck and networking, I'd say, as my best positions were always inbound requests. (Generally: Hey Courtland, we saw that you built cool thing X. Could you build the same for us?) It really helps to be in the financial position to say no to anything that doesn't meet your standards.