New to heart rate training

I recently started heart rate training as I am trying to get back into running from last year. I feel like I can still keep a mid 9 to low 10 min “easy” pace but both my Apple Watch and whoop say my easy pace is mid 13s. Which should I go by for now? 13 feels painfully slow for me but if it will do be better in the long run I’m all here for it