I have found the incremental increases each week just enough of a stretch until that is week 7 . I found it so hard doing 25 mins straight out no breaks that I had to go back and repeat week 6 again as I lost confidence. I had done the 25 mins twice but it was not getting anymore comfortable and I couldn't face continuing. But the runs in week 6 don't feel challenging enough now! It feels like there is a stage missing between week 6 (runs 1 and 2) and week 7 like a 15 min run. I wonder what the science or reasoning is for such a big jump ie from running 10 mins to doing 25 then next session!!!