Zwift Threshold Workout - Fail or Controlled?

The return from run injury continues. I have Benn building my bike fitness, with the hope of racing a Duathlon late August. So I need my Zwift workouts to measure and control the intensity. But sometimes the body does not align with the Zwift workout! That is ok - right? We control the intensity; not Zwift! #duathlon #mastersathlete #zwift #zwiftworkout #agegroup