I am looking to do business or cost analysis?

am looking to become a business analyst and I am wondering what the day to day responsibilties entail? What is a typical day for you? Could someone please tell me what forcasting methodologies or tools that are used. What does forcasting ential? Also, what does budgeting ential? I know its alot but I really need to see if this is for me and prepare for my interviews. Thank you for assisting me