Lifehack outlines the short ways to help improve your mood, on those bad days:
(1) practicing gratitude: "How do you practice gratitude? Several times each day, look at your life
and try to identify the positive things about it. As you do so, let
yourself become fully aware that you might not have had those things in
the first place and that it’s amazing you have them now."
(2) being present: "The basic instructions for becoming present are simple: as you’re doing a
certain activity, you shift your focus from internal to external; you
focus your attention on the activity and the context, thus letting go of
thoughts that take you away from the present moment. For instance, when
you walk down the street, you may be inclined to daydream or dwell on
your problems instead of being present, so this is a great time to
practice this technique."
(3) helping others: "Right now you can go out and buy something nice
for a person in your life and then give it to them, or you can go to
the website of a charity organization and make a donation to support a
cause you believe in."
(4) physical exercise: "Just about anybody who goes jogging, works
out, dances, or plays any type of sports on a regular basis can tell
you that these activities make them feel good. They generally feel
serene, centered and content for hours after doing them. This is because
all these activities are centered around physical exercise: when you
exercise your body, your mind triggers the release of chemicals in your
body that improve your health in the long term. These also give you an
instant mood boost — endorphins, for example, are your body’s natural
feel-good drug."