Of all the characteristics of any painting, colour is the one that speaks the most naturally to our emotions. Bright colours energize and say 'look at me'! Cool blues are calming. Yellows and oranges often feel cheerful. These are generalizations, but the link is there.
Here's a fun exercise for painters to try. Put one of your finished paintings into a program that will globally change the colours. (Even phones often have a setting like this these days.) Play with changing the colours, and think about what happens to the mood as you do.
Another idea - that favourite painting of yours, how about doing it again with completely different colours? Go wild. Or soft and subtle. Just change it up radically for fun.
In teaching art, it is delightful to watch new students discover the freedom they have with colour. It starts simply, 'I think I will do a red tulip instead of the yellow one in my photo.' and then grows into a full blown exploration of replacing colours anywhere in order to be more expressive. A joyful journey.
Whatever stage you are at with your art, I hope you will do some exploring with colour. Understanding the freedom you have is part of what will make your art uniquely yours.