Face your past without regret. Handle your present with confidence. Prepare for the future without fear. Keep faith and drop the fear. Don't believe your doubts and never doubt your beliefs. Life is wonderful if you know how to live it.
There is a line in that quote . . . "Life is wonderful if you know how to live it." It screams life balance to me and learning how to maintain it. I can remember having life balance at different points in my life. Maintaining it is so difficult as life changes and throws us off balance.
Never have regrets for anything in your past since those circumstances have brought you to where you are at this moment and even the bad is good because you learned lessons along the way.
As far as fears and doubts, whatever is going to happen will happen. The present and future are not controlled by fears and doubts unless you are faithless and prevent the process of moving on. Think positively about life situations, make the best choices possible and have faith in the choices you have made for yourself.