Fellow physics to med here. I have a B.Sc. in physics and will be starting at Ottawa this Fall.
You definitely do not need any health-related EC's to be a successful applicant. The first thing you should do is take a look at how all the schools calculate your weighted GPA (e.g., UofT drops lowest marks based on full-time course loads, Ottawa weighs later years more heavily, McMaster just takes your raw cGPA, etc.). Once you take your MCAT, you'll have a better idea of where you stand. Focus on CARS so you raise your chances at Mac.
The importance of ECs can get overblown for Ontario