Data field for workout

Hello.

I have a Garmin Fenix 7 and I want to create a custom data screen for my run training. I am creating some workouts (steps based on distance) and I realized that there's no "distance left" field a available. In the stantard data screen of the workout, there's a field called "Run" where it  shows the distance remaining of that step. That's exactly what I want to use, nevertheless, there's no data field available for custom data screens.

Do you know or do you have a suggestion on how to overcome this limitation?

Thank you.

Best regards,

Luís Martins