The obstacle may be difficult without being mysterious.

Difficulty and mystery feel similar and are not the same. A mysterious problem paralyses you because you have no idea where to begin. A merely difficult one is clear and just hard, and that kind can be worked on steadily. A lot of dread comes from treating the second sort as the first, and giving up on things that only needed hours.

Ask whether you actually do not know what to do or simply do not want to do it. If the steps are visible and unappealing, that is a difficult problem rather than a mysterious one. Start with the first step and let the size of it stop mattering.