How do gym/studio owners determine their pay?

Two colleagues and I are joining forces to open a small studio where we’ll offer personal/small group training, classes, etc. We’re trying to determine the fairest ways to pay ourselves… should we have different rates for each task (i.e. classes vs private vs office admin time vs marketing, etc) or should we set a standardized rate for all? We’re trying to make sure that the three of us are equitably compensated while building up the business in a sustainable way. Any input is hugely appreciated!