Struggling with Motivation and Self-Doubt

How can someone just have motivation? When it comes to doing anything at all especially school work I’m never motivated (don’t get me wrong I love learning) but for some reason I’ve never felt driven to do anything at all. Even the idea of failure and uselessness can’t get me anywhere. All that does is give me terrible anxiety to the point we’re my body can’t think and all I’ll do is bite my nails and space out while tensing up my whole body. My worst fear is being chained to a future that was determined by the efforts that I never put in. I can’t tell if it’s because of my ADD, OCD, Anxiety, or something else. I’m tired of doing so little when I know that I’m capable of so much. Is it possible that every time I don’t understand something that it only ends up proving to myself that I’m incapable of achieving anything adding to my self doubt, distancing myself from the finish line. But even if that is the case… how can I possibly counter something created in my own mind. I have such high expectations and yet at the same time I don’t seem to care. I just want to show myself that I’m smart, and capable. :(