You never know what motivates you.
Quality is not an act, it is a habit.
After a storm comes a calm.
Leap, and the net will appear.
Things do not happen. Things are made to happen.
Be thine own palace, or the world's thy jail.
I can, therefore I am.
If you think you can do it, you can.
The dog that trots about finds a bone.
Problems are not stop signs, they are guidelines.
There's obviously nothing wrong with selling your art - only an idiot with a trust fund would tell you otherwise. But it's confusing to know how far you should take it.