Here are some simple but very powerful things you can do to start feeling better.
They may seem small but they are all help release feel good chemicals in our body and mind:
Do one positive thing today, however small
At the start of the day, write down 3 things you are going to allow yourself to enjoy today (however small)
At the end of the day, write down 3 things you appreciated today (however small).
Listen to a relaxation audio or similar
Exercise or move today - in any way you can manage
Write down 5 of your strengths, things you are good at in any aspect of life
You know that habit you want to change - don't do it (just once) and sit with the discomfort of not doing it just once and see what happens.
Genuinely ask about someone else's life, about how they doing. Remain curious and caring in your questioning even for just a minute or two
Return a smile or offer a smile to a family member, a neighbour or a passer-by
You know that person you are finding difficult at the moment. Write down 10 things they are good at or you admire about them. Go on try it and just see what happens.
As part of a conversation, with yourself or others, notice if you are about to join in negatively and offer a positive possibility instead
Laugh at something or laugh with someone