I don’t have this option in my Garmin Connect
Which Garmin device do you have? Watches compatible with Garmin Coach
Descent MK1
fenix 5 series
fenix 5 Plus series
fenix 6 series
fenix Chronos
Forerunner 45 / 45S
Forerunner 245 series
Forerunner 645 series
Forerunner 935
Forerunner 945
Instinct series
Legacy Hero series (Captain Marvel, First Avenger)
Legacy Saga series (Darth Vader, Rey)
MARQ series
quatix 6
tactix Delta
Venu
vívoactive 3 series
vivoactive 4 / 4S
but still want to use Garmin coach for running training plan...
In that case you will likely need a new device compatible with the feature