Somebody once said to me "you're so lucky you can draw". I disagree, it's not luck, it's the fact that I've been drawing since I can remember. The more you draw, the better you get. I took art at High School and studied art after that. If I had the time, I would paint more. But even when I'm not painting, I'm doodling and drawing in sketchbooks and even in notebooks. If you find yourself drawing or doodling all the time then you just need to keep at it and you will get better.
I call it my play time, when I grab pens, pencils or pencil crayons and just draw, doodle and colour. That's when I let my mind go and just have fun. Through playing, I get ideas and there is something really therapeutic in the feel and sound of the pencil rhythmically moving along the surface of the paper. A sketchbook is not as threatening as the big white canvas, so ideas flow freely.
I have several sketchbooks, two are small enough to carry with me if I want. I will try out ideas, new pens and different drawing styles. I can be as silly as I want. I have another favourite sketchbook, it is an A4 spiral bound book with textured paper and I will often do my pen and pencil sketches in it. Sometimes I will start a drawing, get halfway and just leave it like that. So if you want to draw, then draw and don't worry about mistakes, or feeling "not good enough". You don't have to share them with anyone, just enjoy yourself and have fun.