Maybe because the runs are longer now in week 6/7. As I wanted to get out everyday in the early weeks I did the program 3 days a week, but still went out for 'freestyle' walking and jogging the other days. I thought it improved my fitness so what was the harm?
But after hurting a muscle in my thigh last weekend and resting extra this week I did week 6 run three and actually felt stronger for the rest.
This has actually helped me also get a bit better balance in my life. Now I have allocated some study time on my rest days so I get to work on getting a better paid career in the future. I still do other exercise, swimming once a week and aerobics and some walking (not running) on my treadmill. The aerobics is a high-intensity 15 mins home session and really helps strengthen my core.
And weird thing? I always hope/aim to lose 2lbs a week weight but since doing less I am losing 3lbs a week the last two weeks?
I read somewhere that if you don't rest your body is too busy trying to heal over burning fat?
I don't know. All I know is it's ok to rest! Which doesn't negatively affect your fitness nor ability to burn more calories and gives a better all round life balance!!!
After 13 days rest, I eventually ran today!
Rest days
Days of rest...
Two rest days between every run cheating? 
Rest days
