Perhaps this is a good thread to pose this question. I am a front-end engineer in my early twenties. Right now, 40+ hours a week is doable and I am paid well, but I don't need all of the money I'm earning. I would gladly take a 50% salary cut and work ~20 hours a week. The only problem with this is that I feel like this is a risky thing to bring up with an employer. Has anyone ever had any success getting a good part…
Between now and achieving that 4%, focus on excelling at the things you find the most interesting and building relationships in your industry so that once you cross the freedom line you can take on the occasional consulting gig to keep things interesting.
(I'm pushing 40 now and sincerely wish I had done the above when starting out in my twenties)