What diet and exercise changes do i need if i am going into a high altitude environment?

Water and cardio: It is important to drink more water. Also, doing cardiovascular exercises can help aclimate you to the new environment sooner. I'm presuming that we are discussing places like colorado or similar mountain areas which are typically a mile above sea level. For extreme high altitudes, such as himalayan mountains, there are significant dangers from altitude and that is a more complicated answer.