1. Any particular reason you don't want to take a week off maybe 3-4 times per year? If you're not training for something sport-related where you need to be "on" at all times or don't have a contest coming up, there's no real reason to NOT take a break at least a few times per year, it definitely does a body good. If you're not wanting to take a break because you think you'll either gain fat or lose muscle during that time, don't sweat it, nobody lost their hard work in a 5-7 day rest period unless they did EVERYTHING wrong during that time (such as, eating everything in sight if you're trying to stay lean, or, doing hours of cardio without enough food intake if you're trying to hold on to lean mass gains). It's good to take a break here and there, but if you can't manage a full week, then try for at least 3-4 days off at the end of a week's training cycle, that will at least give you a few extra days in there to rest up.
2. If you WON'T take a break, then at LEAST take a week every season or so where you cut back on the weight used in training significantly, or, cut the time/distance/intensity on cardio work. So, if you normally hit the gym and did weight training for 75 minutes 3-4x/week, take a week where you only go perhaps twice and do a light full-body workout during those days instead of doing a more muscle group specific program again. If you do primarily endurance, instead of running, say, 10 miles 4 times/week, cut it to two days of a light 3-4 mile jog to put less stress on your body for a bit.
If you decide to actually take a week off, just keep the protein high, eat clean, and you'll come back just fine after you're done
There's no magic formula to "rest week" stuff, just that the magic is in actually getting the rest if you haven't taken a break in quite some time!