Yeah, strumming is really hard to think about, and it's definitely not a good idea to think about the down and up strums while doing it. The reason I've got people counting is because I've found that most people who weren't already musical have some trouble with rhythm and timing, and these exercises have really helped a lot. Some people (like you and I) just got strumming straight away, but a lot of people aren't that lucky! I'm always jealous of people who get good, fast, accurate picking straight away - it took me years of hard work before I got good at picking!
