Changing Horses in Mid-Stream
The question was about moving from Sales into Business Analysis, rather than something extreme like "movie director" to "astronaut." Here is the advice I gave:
I would recommend you set up time to meet with your current manager, and discuss these questions with her or him.
It is possible that she will not know the answers to the questions. If that is the case, ask her if she is willing to help you learn the answers -- and support your professional aspirations. Be clear that you are not dissatisfied nor looking to "quit". Be honest with whether you are just exploring ideas, or actively working to make this career transition.
Even if she is not supportive, you can reach out to business analysts at your current company, to learn about their job. Ideally, you could take that learning, and develop a plan to learn the skills that would make you a candidate for an entry level position in your company, doing business analysis.
Perhaps you company offers internal training or even rotation programs, where people from one function can go work in another function for a limited amount of time. That would be an ideal opportunity to go and learn on the job -- and to demonstrate to the managers in the business analysis team that you are a good candidate for future open positions. You may decide that business analysis is not what you want to do. Or you may realize this is your passion, and others will begin to recognize that, as well.