Usually when I'm learning a new programming language or technique, and just at the point where I'm starting to grok it but still having challenges, I'll dream that I'm programming in that language. Usually a day or two after that, I'll feel like I've finally acquired that skill. I remember this very clearly happening when I was about 22 and was playing around with Javascript and AJAX calls. It happened a couple other times after that, I think when learning Objective-C for iOS too, and maybe once again when learning how NSLayoutConstraints work.