Using Procreate, I challenge myself to do very short little doodles, spending only 5-10 minutes each. This exercise forces me to reject perfectionism and let the work flow without focusing on "doing it right."
I've always been a 3D art person - I love tactile work and getting literally dirty producing work. I've been learning more about design and working on growing 2D skills to augment my UX and interaction design work as well.