I know I don't like it either but it is required that you wear a mask while working out now. I actually got in trouble for pulling my mask off while doing the stairs at Planet Fitness. Since that day they have allowed you to remove your mask while doing very strenuous exercises like stair climbing.
As a Certified Fitness Trainer, I do not recommend wearing a mask at all during exercise due to the risk of hyperventilation. However, it is required due to COVID. And I respect that.
I have found a mask that is cool and comfortable and most importantly, breathable. It allows maximum breathing as a mask will allow. I still do not wear mine during extreme exercise.
Here is a link to it on Amazon. I have stocked up on these as I wear one at work and now it is required everywhere. It is only kind to respect the rules without complaining folks!