The human body is an amazing thing...I just did the first run of week four and I was so nervous..I thought I was going to die...but I just got out there and did it and omg...3 minutes is a piece of cake now...5 wasn't even that hard.
It's been 3 weeks people..only 3 weeks. Wow.
Anyway...you can do whatever you want...go for it!
Good luck everyone. We can do it!