Data field that counts down time in HR zone

Hi

I am looking for a data field that works similarly to time in zone but counts down from a target set. Currently I need to remember the times i desire in a zone and use the time elapsed feature. When doing complex training with 4 zones its difficult to remember .

There is the training field that counts down the workout time but this count regardless of what zone your are in. I want to use a training plan that uses time in different zones, but when cycling outside it difficult to go for a 10min in zone 4 when conditions keep changing. I would like to set a goal time in that zone and then see on my screen the time left in that zone