Can someone please explain to me what "endogenous" and "exogenous" conditions affect the business cycle.
I suggest you google the following: economics, endogenous, defined
In an economic model, endogenous variables are items that occur within the model, and are usually predicted by the model. So, in a business cycle model, the level of GDP or the change in GDP would be endogenous.
By contrast, exogenous variables or conditions are givens. They are inputs into the model. They are taken as given. So, variables like population or amounts of natural resources are usually exogenous.