Keeping up motivation when writing

Do you have any tricks to keep up motivation when writing?

As an example, one thing I do is write whatever I have an idea for at the moment, regardless of whether I've written any of the text before or after.

I used to believe I had to figure out a lot more stuff before I could start writing "properly", but it caused me to lose the motivation since I never got to that point.

Writing whatever is in my head at the moment allows me to get going, and fuels me to keep going even after the immediate idea has been brought to paper.