With each having a specific advantage and disadvantage.

Examples: ('class name' = 'advantage' / 'disadvantage'

Brawler = Melee weapons strike harder / melee weapons degenerate faster

Boxer = Fists do more damage & less shock damage taken / must drink more to stay hydrated

Survivalist = Better arrow/bolt ballistics & more bounty gained from nature & less likely to burn food / more affected by fire arms recoil

Ex police officer = Less affected by pistol/shotgun recoil / more affected by rifle recoil

Military veteran = Less affected by rifle recoil / More affected by pistol/shotgun recoil

Limiting sprint by making people get exhausted IMO would open the door for more possibilities:

Fast metabolism = Must eat less to get energized / less sprint time

Athletic = More sprint time / must eat more to get energized