When I ask students to do things that are hard and scary, but set them up to succeed. 
Some of the assignments that I give to students are seen as complicated, tedious, and can be difficult for them.  I acknowledge this fact openly to them, and then tell them that I believe they are each capable of completing the assignment successfully.  Some students come into class with a negative mindset playing in their heads: you can’t do this; you’re going to fail; he will see how stupid you really are. I know those statements are not true, but the students don’t. One remedy for their fear is to give them a quick succession of smaller, achievable assignments, so I break most difficult assignments into smaller tasks, provide frequent opportunities for collaboration with peers, and offer feedback that includes a clear identification of what they’ve done right as well as what needs more practice.