Ok so I did W3R2 yesterday morning. I made the mistake of taking a different route without thinking about it, so it just so happened that every time Laura told me to run I was at the bottom of a steep hill! Silly me!
I was exhausted by the end of it and I can certainly feel it in my legs today - but as Laura says the sense of achievement of getting through a really hard run outweighs the pain at the time. What she doesn't mention is the pain for days afterwards, but I get her point!
My timing was off when I started week 3, so it means my third run of week 3 will roll over to next week. So it's pencilled in for Tuesday - hoping the pain in the legs has dissipated by then!