Regular cardiovascular exercise can increase BMR. Other factors can also affect BMR, such as illness, environmental temperature, and stress levels.
As we age, BMR decreases. Fevers can raise the BMR. Both the heat and cold raise the BMR.
You can read more about BMR at
http://en.wikipedia.org/wiki/Basal_metabolic_rate
If the answer is acceptable please click the accept button so the question can be closed.