There are two ways to look at life: 1. Always be a Pessimist and only good things can happen. 2. Always be an Optimist and shit happens.
I prefer No 2. and learn to deal with the shit that happens as and when. On a personal note of grief, from experience I would always say, never spend your life looking back, you'll miss out on what's infront.
I know what you mean about things not getting to you accept at certain points, I have never seen the point in celebrating new year ever since my uncle died, our last night together was new year. I always feel sad, but at the same time, I try and surround myself with friends/loved ones who know what is going on and it never seems that bad.
In hard times, your friends and family are one of the best things in the world you can ask for.