This week, I've done stamina and Stepping Stones, so Speed seemed like the logical next step.
Foolishly, I reasoned that, as it's a shorter run, I could afford to push myself by lengthening my stride and really going for it...BIG mistake!
First couple of fast intervals were ok, but by the 3rd, I was struggling to get my breath back before it was time for the next one, and my head was screaming for me to walk to recover. Arguing that to date I had never not finished a run since starting C25k, I kept going to finish the whole 6 repeats but had to shorten my stride for the last 2 (whereas I usually speed up to finish a run strongly) and was puffing like a steam train during the cool down.
NOT a pleasant run, not least because there's no time to clear your mind and zone out, lulled by the rhythm of your legs - but I can see how interval training works on improving your breathing and calorie burning.
Anyone else found it tough?