The most difficult thing is the decision to act, the rest is merely tenacity. The fears are paper tigers. You can do anything you decide to do. You can act to change and control your life; and the procedure , the process is its own reward.
Trust your gut instinct over spreadsheets. There are too many variables in the real world that you simply can't put into a spreadsheet. Spreadsheets spit out results from your inexact assumptions and give you a false sense of security. In most cases, your heart and gut are still your best guide.