My training session today was 20 minutes. The aim was to get my heart rate up to 182 and then walk until it dropped to 166 and then run up to 182. I found it incredibly difficult to stay within these parameters. I was dropping far lower and then taking a while to get back up. I think this technique will need a bit more practise. It's made me realise that I only run at comfortably slow or as fast as I can for bursts of intervals. I hope this session will help me to regulate a faster pace.