Culture affects the way people think believe and live. If it affects the way you think by you think about things that happen in your community that involve your culture. If your culture believes in christianity then that will most likely be the religion you study because that is what your culture believes in. If skating is a big thing in your culture you would want to go skating to live like everyone else and enjoy that like everyone else in your community.
Human culture affects nature dramatically. The way humans run an environment controls how nature or other ecosystems adapt to that environment. Such as if humans put a factory and pollute the air, chances are nature will die or will find a way to migrate to a place with better air quality.
Overgrazing results when too many animals graze, eating the grass faster than it can grow.