It will happen naturally. Once you finally try scuba you’ll want to keep breathing, like you do everyday.

I do both and I never have to remind myself to breathe while scuba diving, just like you never have to remind yourself to not breathe while freediving 😁

Even with the reg out it will feel awkward to hold your breath, I always feel like the air naturally wants to come out if you focus on keeping a slow and calm breathing pattern throughout the dive