Re-gain the child-like fun
Give a kid some paper and pencils and just watch them work. They draw anything and everything that comes to mind. They don't care if it's logical or not. A dinosaur driving a sports car in space? Damn right! They're not bogged down by parameters or worried about critique.
It's a stream of pure creative joy. You very rarely hear a small kid getting lost in negative thoughts which prevents them from working.
Sadly, this seems to end when kids get to around 6 or 7. Their understanding of the world is developing, they're developing as people and they become more aware of the thoughts and opinions of other people and this can sometimes seep into their creative endeavours.
They start seeing problems with their work, taking on board these negative feelings and start to lose interest. This is usually when people stop making art outside the classroom. They tell themselves they can't draw and they don't allow themselves to just experiment.
They stop playing with art.
From a young age, people inherently start focussing on the output. It's a mentality which develops in the classroom with subjects which have binary outcomes. English and other languages have rules. Maths at the basic level is binary, an answer to a problem is either right or wrong.
There aren't multiple answers for 2+2...
This mindset does not apply to creativity but often people do so. They focus on the drawing or the sculpture or the short story not being "good". But what they forget to focus on is how they felt while they were doing it.
Even for just a few minutes, did they lose themselves in the doing? Did they enjoy their time sitting on a park bench, drawing a tree while enjoying the sounds of birds or the wind blowing through the leaves?
This is where I want people to focus their energy. Kids don't assess their work as they go, they lose themselves in the act of creating. Then when they're done, they either grab a new piece of paper and do it all over again. Or, they'll go do something else and not let any negative thought about the drawing follow them around or consider it part of their self-worth.
Leave negativity at the door and just be open to having fun making marks on a page, or just thrash out some chords on a piano or guitar... whatever you're into.
If you're really not happy with a drawing then get rid of it. Screw it up, tear it up, even burn it (safely) if you like but as soon as that paper is out of sight, put it out of your mind. Grab another sheet of paper and draw something else.
Keep working on that child-like lack of self-criticism and just have fun letting the creative juices flow.
This is part of a project I've been meaning to do for some time, to write short essays with my thoughts on creating art or creativity in general with the aim to inspire people to get working on something creative.