Step #1 - find a mask that properly fits your face!!! If you're using a "cup style" mask, then try one of the "flat" style masks and vice versa.
Step #2 - REALLY make sure that the moldable metal strip at the top of your mask (whatever style it may be) as properly adjusted to your face! Tape can help with this
Step #3 - practice, practice, practice!! With time and experience, your respiration rate (and likely pulse too 😉 ) will come down when you sit down to work on a patient and you're fogging issues will likely go away
Step #4 - think about if you're exhaling through your nose or mouth. I tended to find that if I exhaled through my mouth that the incidence of fogging was lower than if I exhaled through my nose
Myself personally, the cup style masks just don't fit my face. Never have, never likely will. So I use a flat style, ear loop mask, and I do still too this day spend 5 to 10 seconds everytime I put a new mask on really making sure that the metal strip is properly fit to the shape of my cheeks/nose.
The "best" anti fogging solution that I ever used, was the good 'ol diver's trick. Just take a little of your saliva and rub it on your lenses. Why exactly it works 😕 It just did for me, and I didn't have any of the sometimes "chemically" vapors that anti fog products can emit near my eyes