Exercise to gain stats works if you do not have excess thigh or belly fat (weight gain option) else it removes one unit of this excess fat first.
Exercise works when both strength and dexterity are less then 20, unless you have drunk enough milk. The game keeps track of how many units of milk you have consumed (not just drinking but processed in the stomach).
Every time you gain a stat point through exercise this number drops by one.
Either total units remaining must be greater then (strength - 20) to gain 1 point of strength above 20
Or total units remaining must be greater then (dexterity - 20) to gain 1 point of dexterity above 20
The multiplier for how much exercise you need to do is dependent on this number. It is 25 - Units or 15 if Units > 10.
Moving from room to room gives 1 point of exercise. At the start of the game (without buying more stats through the options) that is 350 rooms. Other ways to increase exercise (that I know of):
fighting: kicking, kneeing, slapping and defeating enemies
movement: swimming
drinking: tincture of acceleration, blessed milk (decant a can of milk into a blessed drinking vessel)
items: cross trainer in the hotel (better result with more exercise themed gear)
