First, living by faith does not mean ignoring your fears or anxieties. It helps to remember that we are complex beings with feelings and thoughts at multiple levels all at the same time. If your body wants to eat candy but your will wants to lose weight, neither choice would be made by somebody other than you. You are not your more authentic self if you give in to a temptation, but you also don't become somebody else.
If you live by faith and there is change and decay and chaos all around you, you should not be surprised if your body and soul feel anxious.