I am around a year (or just under) from retiring early. At first, it was REALLY difficult, but I've done two adjustments:
1. I take pride in my work. I won't do a shoddy job on projects assigned to me. I'm not going to go above or beyond unless I really want to, but the work I do will be competent, complete and up to my usual standards - because I personally care about doing a good job (so it's not for them, it's for me).
2. That being said, I also no longer feel compelled to work my ass off to meet unrealistic deadlines or go out of my way to impress or garner praise or attention, or go above or beyond the job assignment parameters. If I can't meet a deadline with minimal overtime, then I'll tell them that the deadline needs to shift, or the project parameters need adjusting. Simple as that.
I don't care about raises or performance reviews or any of that crap, so as long as I'm doing the best job I'm capable of doing within my own personal boundaries, I don't really care about the rest of it.