Your thoughts and words are cues to your cells about how they should function. If you give them messages like: I feel old, my mind isn't what it used to be, I have no strength anymore - they will work to fulfill these images. Don't dwell on what seems like reality, compliment yourself on how well you are able to remember things, tell yourself how good you feel.
There is a saying that it is easier to act your way into a new way of thinking than to think your way into a new way of acting.
Peace is about the choices that we make - do we hold onto judgments, do we think violent thoughts, do our actions create more conflict and separation, do we make compassionate choices in our clothing, household items and food. Can we offer the compassion we feel for those close to us to those we disagree with, to those with different values and beliefs?
It's not enough to pray for peace, we have to be peace.