The good news is that when you have rest days, take them as rest days! Often, runners get into the routine of their training, and at some point it feels very strange to have days that are for rest. Force yourself to take them when scheduled. Remember, rest and recovery are part of training. That time off helps your body heal so that you are ready for the next workout.
When you have a rest day, sit on the couch guilt-free! Enjoy your day. If you find you must get some activity into your day, take a short and leisure walk.
Remember, the last thing you want to do is wind up mentally or physically burned out and overtrained. Take those schedules days off.