Day 12: lunging
Sorry, I just realised I never posted Day 12 on my website. I hope you still managed to see it on Facebook or twitter. If not it was a lunge. 12 on each leg. Plus your other 11 days.
Not to worry if you didn't do this at the time. If you're new to exercising then this could be your 12 day introductory programme. Try it out!