It is easy to focus on the negative things that happen in our lives.  It is pretty normal, in fact.  Some researchers suggest that this negative focus / bias is a result of our evolutionary adaptation because negative things had a greater tendency to cause us harm or even death than the positive things.  But with a pivot to expressing gratitude for the simple, yet meaningful, things in our lives we can feel better and have a more positive outlook about ourselves, our situation and our future.  There are not many things that we can truly control in our lives, but our mindset and attitude is one of them.  We chose how we respond to our circumstances and we control our perspective about the future.  Expressing a little more gratitude helps to frame both of these in a more balanced manner and in a more positive light.

I would maintain that thanks are the highest form of thought, and that gratitude is happiness doubled by wonder.  Gilbert K. Chesterton

Gratitude is the healthiest of all human emotions. The more you express gratitude for what you have, the more likely you will have even more to express gratitude for.  Zig Ziglar

The roots of all goodness lie in the soil of appreciation for goodness.  Dalai Lama