Four Weeks of 10-20-30 Training

I finished four weeks of 10-20-30 training today. I have completed eight sessions of three 5 interval sets or 120 10-20-30 intervals. I am not exactly sure why I decided to try running the 120th interval without letting my heels touch the ground because previous attempts to do this only resulted in failure. Previous attempts were uncomfortable and I could only take 2-3 steps before my heels hit. Interval number 120 was totally different as I cruised effortlessly through the 10 second sprint and then continued on my toes through the 20 second moderate run. Afterwards I was very impressed at how easy and smooth interval 120 had been but regretted I was done for the day. I have to wait until next week to see if I can do it again. Four weeks of 10-20-30 training has allowed me to go from running 5 seconds on my toes to 30 seconds. My goal for next week is to run all 30 10-20-30 intervals on my toes.