Vision and temperature sensation are both mediated by the nervous system which is very adaptive. It adjusts its sensitivity to attempt to match your current setting. A big change in the setting creates a bit of a shock to the system. Do you know what else is mediated by the nervous system? Movement.
When we become very active after having been relatively still it is the same shock to the nervous system as the bright light or the hot water.
If you don’t let your nervous system re-acclimate to the new setting gradually it can have consequences. The light can bring about a headache if you don’t look away to a dimmer area for a minute and the water can bring about a feeling of having been burnt that may last for several hours. If we don’t re-acclimate our movement we can be left with a sensation of stiffness, soreness, clumsiness, etc. This is the essence of “warming up” before activity.
I don’t know too many people that would stare into that bright light or punish themselves in the hot water without first “warming up.” So, why don’t we do it at work and play? Stop staring into the light!