I'm not nervous this time, so that's a pretty good sign.
When I saw the above, I said to myself, really! I get nervous too sometimes when I'm called to make a presentation or give a talk, I would take a deep breath and then I'm good to go.
You said the gym session you had could probably be the reason why you've been able to combat the above, I would try its working.
Have a great time during the interview session, I'll be looking forward to reading the feedback. I hope you'll later.