I can only think about one thing at a time.
Any girl reading this just going to roll her eyes and think, “Of course. You’re a guy!”. But it’s not just true for me, it’s true for everyone. It’s true for you.
And not in that way.
At first, this claim can sound fantastic. We can talk on a cell phone while driving to work, and we can compose complex sentences while typing. But, if you stop to reflect on it, you can only do those things at the same time because at least one of them is automatic. In the first case driving is automatic, and in the second case typing is automatic. You’ve done them so often that you’ve habituated to them: doing them doesn’t require any thinking. Can you still talk on your cell phone while driving through a rainstorm on unfamiliar roads? Would you still be able to concentrate on writing if you had just switched to a Dvorak keyboard? I didn’t think so.