you sure have a good combination of credentials. More often than not, I feel that I should have a degree in counseling.
The closest to a bridge between the two that I can think of would be a coaching certification. One of the options is the ACE Lifestyle and Weight Management Coach certification.
On the other hand, I am not sure you even need an extra certification. If you have your credentials in both fields, I will ultimately be up to you how you combine them.
I am not familiar with the licensing requirements for a therapist; you may need to check with them as well. Personal training is not reimbursed by health insurance companies but counseling often is. That may be something to think about if you create a hybrid offer.
Hope this helps.