Why is 去 ("to go") in 也不去考虑以后会是怎样 ("...and don't think about how it will be in the future")?
It's an interesting question. 

It's worth to know that "(不)去 + verb" can be considered as a fixed expression in Chinese. For example, （不）去做，（不）去想， （不）去听， （不）去玩， （不）去说，... ...

The literal meaning of （不）去 is "（not） to go". Let's say 我去看你， meaning I go see you. 

Its literal meaning can be extended when the following verb doesn't require you to go literally, such as the verb 想, 听，说 and etc. It implies that you would get another place or take another time to do something. I found this dictionary definition can help: 


  
  用在另一个动词前， 表示要做某事.
  
  
  你去问一问：please go and ask. 
  
  我们自己去想办法： We'll find a way out ourselves.


For more detailed explanation, 我去考虑一下 vs 我考虑一下, 我去考虑一下 means I will go offline to think about it or I will take another time to think about it. Well, 我考虑一下 doesn't specify when I will think about it and it could mean to think about it right now or I will think about later on(offline). 

Hope this can help.