One of the things i've observed is the feeling of how negativity can become a reinforcing cycle, which is a topic commonly talked about.
To help escape the cycle there are few things.
You can block out and get rid of negative influences. This can often force yourself to adapt and change, to break patterns.
Spreading positivity and extending good vibes can help bring postivity back to you. But also (although it might seem obvious) laughing enjoying things, smiling etc.
Stop and take time to be aware of things. Breathe. Try to see different sides of the situation. Also try to focus on the moment rather than the past, be mindful of what is around you.