Easiest way to inner peace is to resolve yourself that the only thing you have any control over is your own actions. Whatever else happens was going to happen regardless. Then you can focus on reacting with yourself to what must be reacted to.
As soon as I started to think this way, my life changed. Now even people close to me dying doesn't bother me. Anger is not part of my life. If I get angery, it is by choice and my own will to get angery, I have to actually make a decision to start becoming angery.
You shoot me, and as long as I didn't provoke you, I would not be angery. There was nothing I could have done to prevent it, so why worry?
This philosophy combined with my pure Christian faith (meaning my own death will be a happy occasion for me) makes me nearly unshakeable. The only emotions I have are guilt and love. Love is from my faith, and is for all. Guilt is when I fail in keeping my actions pure. Those are all I have to deal with. Joy is part of love for those wondering. Anger is part of guilt, because they only time I ever choose to be angery is at myself for my failings.