First year teaching marine biology and physics. Any advice please!

Hi everyone, I am a first year teacher. I was initially hired to teach high school environmental science but was switched to marine bio the first day of pre planning. I just also found out I have to teach a period of physics. Physics is probably my weakest subject and I am super nervous about having two curriculums on top of learning how to be a teacher. I’m feeling very overwhelmed right now if anyone has any advice!