It is not self-assertion when you do something, because you love to do it.
When you write and paint – not because you want prestige, but because you love to write and paint – it is assuredly not self-assertion.
Self-assertion occurs when you compare yourself with other writers or artists, when you want to distance them.
This would be the will to power, and the will to power is self-assertion.
But it is not self-assertion, when you do something, because you really love to do it.
This is passion. And passion is love.