I take time for mindfulness. In life, we all struggle and feel down at times. It's ok to feel that way for brief moments, particularly if you've faced some challenges. It's not ok to dwell though, so I focus consciously on what I do have that I am grateful for, what does make life beautiful - and what I can do to lift myself up.
It's really amazing how taking 10 to 15 minutes to meditate and think only of what you are grateful for can change your outlook. It can start off simple - I am grateful for the sunshine this morning, or thankful for the softness of my pillow etc. and then it builds. Write it down, draw it out, really focus on feeling that gratitude deep in your heart and soul.
Other times, I take the opposite approach and get completely out of my own head and I do things for others, even strangers I don't know. I know that when I'm hurting I appreciate a little gift or sign, so I become that gift. Open doors for people, smile at them, ask them how they are and mean it, compliment them on something unique, give something to those who need it more than you - all of these things help me feel reconnected to my fellow humans again and that is uplifting.