The human body tries to maintain favorable conditions. If you have low blood sugar, you feel hungry and you eat to increase your blood sugar.
Body etmperature is like that. For example, shivering produces heat by contracting and releasing muscles rapidly and repeatedly to increase body temperature. And sweating removes heat from the body to decrease body temperature.
Now this cannot indefinitely; outside temperature can be so high that your body cannot cool off in a reasonable amount of time. This is a medical condition and requires immediate attention as it can lead to death if left unattended.
PS: I think this question belongs under Biology.
