One simple way of instantly reducing negativity and start feeling better, is to do an alphabetized gratitude inventory. I often do this as I'm going to bed, it's excellent to clear my mind of all the stress and practical issues of the day and also to reclaim a positive focus.
This mental exercise is really simple, just start repeating the alphabet and for each letter you think of one thing in your life that you are grateful for.
A: my Apartment
B: Blue sky today