I am now doing this C25K programme - but when I first looked at it 2 months ago , I decided that for me (at age 68) it was too much for me. So I did this one from the Mayo Clinic instead mayoclinic.org/5k-run/art-2... Designed by the quite famous marathon runner Jeff Galloway, it starts out much more gently - with run/walk periods of only 13seconds/45seconds -- but for 30 minutes instead of this NHS C25K programme of 20 minutes. It was ideal for me and I got right through the 9 weeks easily ( anyone? can run for 15 seconds !) and, I started to do Parkruns with it after a few weeks, averaging around 38 minutes for the 5K, with weekly runs up to 7 K long . I am now up to week 3 of the NHS C25k and finding the longer running periods to be my downfall. But I will try to keep it up and see how I go.